Hydraulic fluids from renewable isoparaffins

ABSTRACT

A hydraulic fluid comprising a biobased base oil having hydrolytic stability.

The present disclosure generally relates to hydraulic fluids. In one embodiment, the disclosure relates to biobased hydraulic fluids comprising a biobased hydrocarbon such as isoparaffinic hydrocarbon derived from hydrocarbon terpenes such as myrcene, ocimene and farnesene.

Mineral oils from petroleum, natural oils from plants and animals, and synthetic esters such as polyol esters and poly-alpha-olefins (PAOs) are commonly used as base oils for hydraulic fluids and similar lubricants. Hydraulic fluids typically consist of 60-100% base oil by weight with the remainder in additives to provide various fluid properties, such as improved low temperature behavior, oxidative stability, demulsibility, and other properties, such as corrosion protection and wear protection. While the commercially available fluids traditionally used have advantages and attractive properties, they also have some disadvantages. For example, and depending, depending upon the base oil selected, a commercially available hydraulic fluid may have poor low temperature fluidity, poor fire resistance, poor thermal oxidative stability, and/or poor biodegradability.

The primary purpose of hydraulic fluids is to maintain lubrication and fluid characteristics while in use within a system so as to maintain appropriate pressure to operate hydraulic actuators (cylinders/motors) or assemblies in machinery on demand. In order for appropriate pressures to be maintained within a hydraulic system, the fluid is constantly being run through a pump. The constant pumping action creates a substantial buildup of heat in use, which hydraulic fluid must withstand. Additionally, the operation of the hydraulic actuators and the process of constantly pumping the hydraulic fluid subjects the fluid to constant mechanical stresses. Mechanical sheer forces operate to degrade hydraulic fluids.

Hydraulic oils are unique lubricants due to their widespread use in all forms of equipment operating in a wide range of environments. The pressure in a hydraulic system creates a situation where leaks are common. Since many pieces of hydraulic equipment are operated in environments with environmental sensitivity such as in and around water, mining, agriculture, and food, a more environmentally friendly hydraulic oil is highly desirable to industry. The desire for these properties is shown by the growth of the biobased hydraulic oil segment and increasing legislation around the world mandating the use of these products. Unfortunately the development of this market has been slow due to the performance limitations of the biobased hydraulic fluids that can meet the renewability and/or biodegradability requirements of the products.

Biobased hydraulic fluids have traditionally been based on natural or synthetic ester products. This has allowed the products to be strong in the areas of renewability and biodegradability but weak in some of the classical performance areas of a hydraulic fluid as provided by the more typical hydrocarbon base oils. These main limitations are around hydrolytic stability, seal and material compatibility, oxidation stability, cold weather performance, and compatibility with existing non-biobased hydraulic oils.

Specifications for hydraulic fluids based on mineral oils (H) are described in ISO 11158 [1] and the specifications for fire-resistant hydraulic fluids (HF) are given in ISO 12922 [2]. Test methods and criteria for performance are relatively well defined for these two categories of hydraulic fluids compared to the relatively new class of environmentally acceptable hydraulic fluids (HE). This last type has come into existence mainly because of the need for non-toxic biodegradable fluids which are compatible with the environment. The specifications for the different types of hydraulic fluids do not line up and in particular HE fluids do not match the performance expectations of the H and HF fluids. The Denison hydraulic fluid specifications are listed below in Table I and the specification for ISO 15380 Environmentally Acceptable Hydraulic Fluids is shown in Table II.

TABLE I TEST Procedure HF-0 HF-1 HF-2 Viscosity cSt at 40° C. ASTM D-446 Report Report Report Viscosity cSt at 100° C. ASTM D-446 Report Report Report Viscosity Index ASTM D-2270 90 min 90 min 90 min Gravity API (specific) 840 to 900 840 to 900 840 to 900 Zinc, % wt Report Report Report Pour Point ASTM D-97 </=−20° C. </=−20° C. </=−20° C. Aniline Point ASTM D-611 >100° C. [3] >100° C. [3] >100° C. [3] Flash Point ASTM D-92 Report Report Report Acid Number ASTM D-664 Report Report Report Rust Test Distilled Water ASTM D-665A No rust No rust No rust Synthetic Sea Water ASTM D-665B No rust No rust No rust Foam Allowable Foam after 10 min ASTM D-892 None None None Filterability [1] Filtration Time without Water TP-02100 [4] [6] [4] [6] [4] [6] Filtration Time with 2% Water (Denison) [4] [6] [4] [6] [4] [6] Demulsibility ASTM D-1401 40/37/3(30 min) 40/37/3(30 min) 40/37/3(30 min) Sludge and Corrosion ASTM D-4310 [2] Neutralization Number after 1 mg KOH/g 1 mg KOH/g 1 mg KOH/g 1000 hrs maxi Insoluble Sludge maxi 100 mg 100 mg 100 mg Total Copper maxi 200 mg 200 mg 200 mg Thermal Stability CINCINATI After 168 hours at 135° C. P70 (ISO 46) Sludge maxi 100 mg/100 ml 100 mg/100 ml 100 mg/100 ml Copper wt Loss 10 mg 10 mg 10 mg Copper Rod Rating Report Report Report Hydraulic Stability ASTM D-2619 Copper Specimen wt Loss maxi 0.2 mg/cm² 0.2 mg/cm² 0.2 mg/cm² Acidity of Water Layer maxi 4.0 mg KOH/g 4.0 mg KOH/g 4.0 mg KOH/g FZG. Load Stage before damage DIN 51524 Teil 2 9 min 9 min 9 min Deaeration (ISO 32) @ 41° C. NFT 60149 @ <10 min <10 min <10 min Deaeration (ISO 46) @ 50° C. 30 cSt constant <7 min <7 min <7 min Deaeration (ISO 68) @ 59° C. <4 min <4 min <4 min Pump Wear maxi for 5 pistons T6H20C 300 mg 300 mg Pump Wear maxi [vanes + pins] 15 mg 15 mg Shear Test (High VI only) KRL (20 hrs) 15% 15% 15% T6H20C after 307 hrs [5] [5] [5] after 608 hrs [5] [5] [5]

TABLE II Environmentaly acceptable hydraulic fluids HETG HEPG HEES HEPR Base Oil Material Triglyceride Polyglycol Synthetic Ester PAO Density 15 C. ISO 12185 Report Report Report Report Color ISO 2049 Report Report Report Report Appearance at 25 DeC Bright and Clear Bright and Clear Bright and Clear Bright and Clear Ash content, max. ISO 6245 No Specification No Specification No Specification No Specification Flash point, Cleveland open ISO 2592 185 C. 185 C. 185 C. 140 C. cup, min. KV −20 C. Max ISO 3104 No Specification No Specification No Specification No Specification KV 0 C. Max ISO 3104 780 mm{circumflex over ( )}2/s 780 mm{circumflex over ( )}2/s 780 mm{circumflex over ( )}2/s 780 mm{circumflex over ( )}2/s KV 40 C. Min to Max ISO 3104 41.4 to 50.6 mm{circumflex over ( )}2/s 41.4 to 50.6 mm{circumflex over ( )}2/s 41.4 to 50.6 mm{circumflex over ( )}2/s 41.4 to 50.6 mm{circumflex over ( )}2/s KV 100 C. Min ISO 3104 6.1 6.1 6.1 6.1 Pour point. max. ISO 3016 No Specification −15 C. −15 C. −15 C. Low temperature fluidity after 7 days ASTM D2532 No Specification No Specification No Specification No Specification Acid number, max. ISO 6618 No Specification No Specification No Specification No Specification Water content max. ISO 12937 1000 mg/kg 5000 mg/kg 1000 mg/kg 1000 mg/kg Copper corrosion, 100 DC, 3 h, max. ISO 2160 2 2 2 2 Rust prevention, procedure A ISO 7120 Pass Pass Pass Pass Foam at 24 C. max ISO 6247 150/0 150/0 150/0 150/0 Foam at 93 C. max ISO 6247  75/0  75/0  75/0  75/0 Foam at 24 C. max ISO 6247 150/0 150/0 150/0 300/0 Air release, 50 DC, max. ISO 9120 10 10 10 10 Water separation ISO 6614 No Specification No Specification No Specification No Specification Elastomer compatibility after 1000 h ISO 6072 at given test temperature NBR 1 80 C. — 80 C. — HNBR 80 C. 100 C. 80 C. 100 C. FPMAC 6 80 C. 100 C. 80 C. 100 C. Change in Shore-A-hardness, max. ±10 ±10 ±10 ±10 Change in volume, max. −3 to +10% −3 to +10% −3 to +10% −3 to +10% Change in elongation, max. 30% 30% 30% 30% Change in tensile strength, max. 30% 30% 30% 30% Oxidation stability Time to reach A5TM 0943 IITAN = 2 mg KOHIg, min. Report, No Specification 1000 1000 reach, Report, No Specification HAN = 2 mg KOH/g, min. Baader test, 95° C., 72 h DIN 51554-3 Increase in viscosity at 40 OCt max. 20% No Specification 20% Load carrying properties, FZG !V8, 3190, min. DIN 51354-2 10 10 10 10 Vane pump IP 281 Ring, max. CETOP RP67H 120 mg 120 mg 120 mg 120 mg Vane, max. DIN 51389-2 30 mg 30 mg 30 mg 30 mg Biodegradability, min. ISO 14593 60% 60% 60% 60% Acute fish toxicity, 96 h, LC50, min. ISO 7346-2 100 mg/l 100 mg/l 100 mg/l 100 mg/l Acute Daphnia toxicity, 48 h, ISO 6341 100 mg/l 100 mg/l 100 mg/l 100 mg/l EC50, min. Bacterial inhibition, 3 h, EC50, min. ISO 8192 100 mg/l 100 mg/l 100 mg/l 100 mg/l

The market demand and importance of biobased hydraulic fluids is growing and a technology that can provide the hydraulic oil performance that is required by the industry along with the green characteristics is sorely needed. Commonly used base oils often fail to bring together a high level of environmental performance such as biodegradability with traditional lubricant performance characteristics. Thus, there continues to be interest in new fluids that can provide better environmental performance while also providing sound lubricant performance.

An Ecolabel guidance has been issued for hydraulic fluids and the key guidance is that it must be >50% renewable, contain >90% by weight of materials that are biodegradable, none of the formulation components can have any health or environmental R-phrases or H-Statements, no CMR 1 or 2, no metals except Na, K, Ca, Mg, no organic halogens, no nitrates >0.1%, and it must pass aquatic toxicity and bioaccumulation requirements.

Biodegradability can be determined using one or more standardized test procedures and can provide valuable insight in comparing the potential risk of different lubricant products to the environment. One such guideline and test method has been set by the Organization for Economic Cooperation and Development (OECD) for degradation and accumulation testing.

The OECD has indicated that several tests may be used to determine the “ready biodegradability” of organic chemicals. Among these, aerobic ready biodegradability by the OECD 301B method tests material over a 28-day period and determines biodegradation of the material by measuring the evolution of carbon dioxide from the microbial oxidation of the material's organic carbon. The carbon dioxide produced is trapped in barium hydroxide solution and is quantified by titration of residual hydroxide with standardized hydrogen chloride. To determine the percent biodegradation, the amount of carbon dioxide produced microbially from the test material is compared to its theoretical carbon dioxide content (the complete oxidation of the carbon in the test material to CO₂). Positive controls, using sodium benzoate as a reference material, are run to check the viability of the aerobic microorganisms used in the procedure. Blank controls are also run in parallel. Tests, controls, and blanks are run in duplicate.

Using the OECD 301B method (28-day period) for comparison, isoparaffinic oil based hydraulic fluid has lower biodegradation than other commercially used and environmentally preferred biodegradable hydraulic fluids such as natural and synthetic ester based hydraulic fluids. Isoparaffinic oil has great difficulty meeting the industry standard for biodegradability of >60% in the OECD301B test in 28 day. Also, the production of isoparaffinic oil still depends on depleting natural resources and thus has an adverse impact on carbon neutrality (carbon footprint balance).

Renewable (a.k.a. natural) ester based hydraulic fluid has two major advantages over other hydraulic fluids mentioned above, higher flash point and great biodegradability. However, many of the non-renewable ester based fluids are not considered to be biodegradable in a reasonable time frame. In recent years, regulatory agencies have become increasingly concerned about oil spills which can contaminate the ground soil and other areas.

Among the various aspects of the disclosure, therefore, may be noted the provision of a hydraulic fluid offering certain environmental performance characteristics, the provision of a biodegradable hydraulic fluid, the provision of a hydraulic fluid comprising a biobased hydrocarbon, and the provision of clean biodegradable alternative hydrocarbon products which have improved environmental performance and/or physical properties such as better oxidative stability, low volatility, improved separation of oil from water (and air), and anti-wear properties.

Briefly, therefore, one aspect of the present disclosure is a hydraulic fluid comprising a hydrocarbon biobased base oil having an average molecular weight (weight average) between 300 g/mol and 900 g/mol, and an additive package, the additive package comprising an anti-oxidant.

Another aspect of the present disclosure is a hydraulic fluid comprising a biobased hydrocarbon base oil, the hydraulic fluid having a biodegradable rate in excess of 60% as determined in accordance with OECD 301B.

Another aspect of the present disclosure is a hydraulic fluid comprising a biobased base oil, wherein at least about 20% of the carbon atoms in the biobased base oil originate from a renewable carbon source and the hydraulic fluid meets Denison Hydraulics standard HF-0.

Another aspect of the present disclosure is a hydraulic fluid comprising a biobased base oil wherein at least about 20% of the carbon atoms in the biobased base oil originate from a renewable carbon source and the hydraulic fluid has a TAN <2 at 1000 hours as determined in accordance with ASTM D943-04a (2010)e1.

Another aspect of the present disclosure is a hydraulic fluid comprising a biobased hydrocarbon base oil, wherein at least about 20% of the carbon atoms in the biobased base oil originate from a renewable carbon source and the hydraulic fluid has a pour point of less than 40° C.

Another aspect of the present disclosure is a hydraulic fluid comprising a biobased hydrocarbon base oil, the hydraulic fluid having a biodegradable rate in excess of 60% as determined in accordance with OECD 301B.

Another aspect of the present disclosure is a hydraulic fluid comprising a biobased base oil having the molecular structure:

[B]_(n)—[P]_(m)

where,

-   -   [B] is biobased hydrocarbon repeating unit;     -   [P] is non-biobased hydrocarbon repeating unit;     -   n is greater than 1, and m is less than 4;     -   the stereoscopic arrangement of [B] and [P] repeating unit can         be linear, branched, and cyclic.     -   the sequential arrangement of [B] and [P] can be block,         alternating or random; and     -   the molecular weight is in range of 300 g/mol to 900 g/mol; and     -   the biobased content of the hydraulic fluid is greater than 20%,         as measured by ASTM D6866-12.

Another aspect of the present disclosure is a biobased hydraulic fluid that can be mixed with a Group I, Group II, or Group III hydraulic fluid and used for top off in the field.

Another aspect of the present disclosure is a formulated hydraulic fluid, said hydraulic fluid having an ISO viscosity grade of 2 to 46,000 and comprising:

(a) 1 to 95 wt % of at least one base oil containing carbon from a renewable source; and

(b)(i) 5 to 50 wt % of at least one first basestock selected from Group I basestocks having a viscosity range of from 3 cSt to 50 cSt, Group II and Group III hydroprocessed basestocks, and a Group IV PAO having a VI of about 130 or less; or

(b)(ii) 1 to 50 wt % of a second basestock selected from Group V basestocks.

Another aspect of the present disclosure is a hydraulic fluid comprising: (a) a base oil having a weight average molecular weight in the range of 400 to 600 g/mol, a viscosity index greater than 120 and less than 140; and (b) an anti-wear hydraulic oil additive package; wherein the hydraulic fluid has (i) an air release by ASTM D 3427-012 of less than 0.8 minutes at 50° C., and (ii) a Sequence II foam tendency by ASTM D 892-13 of less than 50 ml, and a biodegradability rate of at least 60% as determined by OECD 301B.

Another aspect of the present disclosure is a hydraulic fluid comprising a biobased hydrocarbon base oil, the hydraulic fluid being compatible with and suitable for mixing with a Group I, Group II, or Group III hydraulic fluid.

Another aspect of the present disclosure is an apparatus comprising a pump lubricated by a hydraulic fluid as described in any of the preceding paragraphs.

Another aspect of the present disclosure is a gear system, circulation lubrication system, hydraulic system, compressor system, vacuum pump, metal working machinery, electrical switch or connector comprising a hydraulic fluid, the improvement comprising a hydraulic fluid according to any preceding paragraph.

Other aspects, features and embodiments of the present disclosure will be, in part, discussed and, in part, apparent in the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot comparing biodegradability of different types of base oils using the OECD 301B method.

FIG. 2 is a plot showing the percentage biodegradation of hydraulic oil formulated with biobased base oils according to one embodiment of the present disclosure, Exp-Hyd.BL.1, over a period of 28 days.

DETAILED DESCRIPTION

Base oils, and more particularly isoparaffins, derived from biobased hydrocarbon terpenes such as myrcene, ocimene and farnesene, have been described in PCT Patent Application No. PCT/US2012/024926, entitled “Base Oils and Methods for Making the Same,” filed, Feb. 13, 2012 and published as WO 2012/141784 on Oct. 18, 2012, by Nicholas Ohler, et al., and assigned to Amyris, Inc. in Emeryville, Calif. These base oils have been stated to have utility as lubricant base stocks.

WO 2012/141784 discloses that terpenes are capable of being derived from isopentyl pyrophosphate or dimethylallyl pyrophosphate and the term “terpene” encompasses hemiterpenes, monoterpenes, sesquiterpenes, diterpenees, sesterterpenes, triterpenes, tetraterpenes and polyterpenes. A hydrocarbon terpene contains only hydrogen and carbon atoms and no heteroatoms such as oxygen, and in some embodiments has the general formula (C₅H₈)_(n), where n is 1 or greater. A “conjugated terpene” or “conjugated hydrocarbon terpene” refers to a terpene comprising at least one conjugated diene moiety. The conjugated diene moiety of a conjugated terpene may have any stereochemistry (e.g., cis or trans) and may be part of a longer conjugated segment of a terpene, e.g., the conjugated diene moiety may be part of a conjugated triene moiety. Hydrocarbon terpenes also encompass monoterpenoids, sesquiterpenoids, diterpenoids, triterpenoids, tetraterpenoids, and polyterpenoids that exhibit the same carbon skeleton as the corresponding terpene but have either fewer or additional hydrogen atoms than the corresponding terpene, e.g., terpenoids having 2 fewer, 4 fewer, or 6 fewer hydrogen atoms than the corresponding terpene, or terpenoids having 2-additional 4-additional, or 6-additional hydrogen atoms than the corresponding terpene. Some non-limiting examples of conjugated hydrocarbon terpenes include isoprene, myrcene, α-ocimene, β-ocimene, α-farnesene, β-farnesene, β-springene, geranylfarnesene, neophytadiene, cis-phyta-1,3-diene, trans-phyta-1,3-diene, isodehydrosqualene, isosqualane precursor I, and isosqualane precursor II. The terms terpene and isoprenoids may be used interchangeably and are a large and varied class of organic molecules that can be produced by a wide variety of plants and some insects. Some terpenes or isoprenoid compounds can also be made from organic compounds such as sugars by microorganisms, including bioengineered microorganisms, such as yeast. Because terpenes or isoprenoid compounds can be obtained from various renewable sources, they are useful monomers for making eco-friendly and renewable base oils. In some embodiments, the conjugated hydrocarbon terpenes are derived from microorganisms using a renewable carbon source, such as a sugar.

Further processing of certain of such biobased base oil stocks has been found to yield highly useful and superior hydraulic fluids. For example, C15 hydrocarbons containing four double bonds such as Biofene™ β-farnesene, commercially available from Amyris, Inc. (Emeryville, Calif.) may be pre-treated to eliminate impurities and then hydrogenated so that three of the four double bonds are reduced to single bonds. The partially hydrogenated intermediate product is then subjected to an oligomerization reaction with a linear alpha-olefin (LAO) using a catalyst such as BF₃ or a BF₃ complex. A further intermediate product, consisting of a mixture of hydrocarbons ranging from C10 to about C75, results. This oligomeric mixture of hydrocarbons is then hydrogenated to reduce the amount of unsaturation. The saturated hydrocarbon mixture is then distilled to obtain the targeted composition and finally blended to meet desirable base oil product specifications (such as kinematic viscosity at 40° C.) for the hydraulic fluid. Desirable examples of biobased base oil specifications that can be used to produce blends suitable for hydraulic fluid formulation for one embodiment are set forth in Table III. In some embodiments in this disclosure, a commercially available biobased hydrocarbon base oil (a partially hydrogenated β-3,7,11-trimethyldodeca-1,3,6,10-tetraene reaction products with linear C8-C16 alpha-olefin hydrogenated) sold under the commercial designation NOVASPEC (Novvi LLC, Emeryville, Calif., United States; (REACH registration number 01-2120031429-59-0000), is used.

In preparing a hydraulic fluid with the exemplary biobased hydrocarbon base oil of Table III, or another biobased hydrocarbon base oil of the present disclosure, about 20 weight percent (wt %) up to about 100 wt % of the biobased hydrocarbon base oil may be used. To this biobased hydrocarbon oil may be added between about 1 ppm to about 20 wt % additives, namely one or more antioxidants, anti-wear/extreme pressure additives, rust and corrosion inhibitors, metal deactivators, thickeners, viscosity index (VI) improvers, pour point depressants, co-solvents, friction modifiers, foam inhibitors, and/or demulsifiers for a hydraulic fluid formulation. A blend component comprising one or more oils or liquids may also be used as the base oil to formulate or complete the hydraulic fluid, or to adjust the viscosity of the fluid or some other desired characteristic. Such additive oils or liquids may be selected from one or more of the following: microbial oils, vegetable oils, seed oils, mineral oils, isoparaffinic hydrocarbon fluids, silicone fluids, synthetic esters, poly alpha-olefins, polysiloxanes, pentaerythritol esters, poly(butane) liquids, and combinations thereof. The particular additives and the quantity of each used are selected with desired performances and intended use in mind. Other biobased oils may be used as a base oil in a similar manner, with attention to viscosity as with the biobased hydrocarbon base oil.

TABLE III Example Biobased Base Oil Specifications 4 cSt 7 cSt 12 cSt 3 cSt base base base Properties Method base oil oil oil oil Appearance Visual Bright Bright Bright Bright and and and and Clear Clear Clear Clear Color ASTM 0.5 0.5 0.5 0.5 D1500 Density, 15° C. (kg/l) ASTM 0.82 0.82 0.82 0.82 D4052 Viscosity, 40° C. ASTM 12.5 19.2 46.1 105.5 (cSt) D445-14a Viscosity, 100° C. ASTM 3.1 4.2 7.5 12.3 (cSt) D445-14a Viscosity Index ASTM 110 124 126 122 D445-14a Pour point (° C.) ASTM −60 −42 −51 −42 D97-12 Flash point (° C.) ASTM 188 226 254 280 D92-12b

As used herein, biobased base oil is understood to mean any biologically derived oil to be used as a base oil in a hydraulic fluid. Such oils may be made, for non-limiting example, from biological organisms designed to manufacture specific oils, as discussed in PCT Patent Application No. PCT/US2012/024926, published as WO 2012/141784, cited above, but do not include petroleum distilled or processed oils such as for non-limiting example mineral oils. A suitable method to assess materials derived from renewable resources is through ASTM D6866-12, “Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis.” Counts from ¹⁴C in a sample can be compared directly or through secondary standards to SRM 4990C. A measurement of 0% ¹⁴C relative to the appropriate standard indicates carbon originating entirely from fossils (e.g., petroleum based). A measurement of 100% ¹⁴C indicates carbon originating entirely from modern sources. A measurement of >100% ¹⁴C indicates the source of carbon has an age of more than several years. See, e.g., WO 2012/141784, incorporated herein by reference.

Advantageously, in certain embodiments, at least about 20% of the carbon atoms in the base oil comprised by a hydraulic fluid originate from renewable carbon sources. For example, in one such embodiment at least about 30% of the carbon atoms in the base oil comprised by a hydraulic fluid originate from renewable carbon sources. By way of further example, in one such embodiment at least about 40% of the carbon atoms in the base oil comprised by a hydraulic fluid originate from renewable carbon sources. By way of further example, in one such embodiment at least about 50% of the carbon atoms in the base oil comprised by a hydraulic fluid originate from renewable carbon sources. By way of further example, in one such embodiment at least about 60% of the carbon atoms in the base oil comprised by a hydraulic fluid originate from renewable carbon sources. By way of further example, in one such embodiment at least about 70% of the carbon atoms in the base oil comprised by a hydraulic fluid originate from renewable carbon sources. By way of further example, in one such embodiment at least about 80% of the carbon atoms in the base oil comprised by a hydraulic fluid originate from renewable carbon sources. By way of further example, in one such embodiment at least about 90% of the carbon atoms in the base oil comprised by a hydraulic fluid originate from renewable carbon sources. In some variations, the carbon atoms of the base oil component of the hydraulic fluid comprises at least about 95%, at least about 97%, at least about 99%, or about 100% of originate from renewable carbon sources. The origin of carbon atoms in the reaction product adducts may be determined by any suitable method, including but not limited to reaction mechanism combined with analytical results that demonstrate structure and/or molecular weight of adducts, or by carbon dating (e.g., according to ASTM D6866-12 “Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis,” which is incorporated herein by reference in its entirety). For example, using ASTM D6866-12 or another suitable technique, a ratio of carbon 14 to carbon 12 isotopes in the biobased base oil can be measured by liquid scintillation counting and/or isotope ratio mass spectroscopy to determine the amount of modern carbon content in the sample. A measurement of no modern carbon content indicates all carbon is derived from fossil fuels. A sample derived from renewable carbon sources will indicate a concomitant amount of modern carbon content, up to 100%.

In some embodiments of this disclosure, one or more repeating units of a biobased hydrocarbon base oil is a specific species of partially hydrogenated conjugated hydrocarbon terpenes. Such specific species of partially hydrogenated conjugated terpenes may or may not be produced by a hydrogenation process. In certain variations, a partially hydrogenated hydrocarbon terpene species is prepared by a method that includes one or more steps in addition to or other than catalytic hydrogenation.

Non-limiting examples of specific species partially hydrogenated conjugated hydrocarbon terpenes include any of the structures provided herein for dihydrofarnesene, tetrahydrofarnesene, and hexahydrofarnesene; any of the structures provided herein for dihydromyrcene and tetrahydromyrcene; and any of the structures provided herein for dihydroocimene and tetrahydroocimene.

One example of a particular species of partially hydrogenated conjugated hydrocarbon terpene that may have utility as a feedstock is a terminal olefin having a saturated hydrocarbon tail with structure (A11):

where n=I, 2, 3, or 4.

In some variations, a mono-olefinic alpha-olefin having structure A11 may be derived from a conjugated hydrocarbon terpene wherein the conjugated diene is at the 1,3-position of the terpene. Examples include alpha-olefins derived from a 1,3-diene conjugated hydrocarbon terpene (e.g., a C10-C30 conjugated hydrocarbon terpene such as farnesene, myrcene, ocimene, springene, geranylfarnesene, neophytadiene, trans-phyta-1,3-diene, or cz's-phyta-1,3-diene). Another non-limiting example of an alpha-olefin having the general structure A11 includes 3,7,11-trimethyldodecene having structure A12.

A mono-olefinic alpha-olefin having structure A11 may be prepared from the appropriate conjugated hydrocarbon terpene using any suitable method. In some variations, the mono-olefinic alpha-olefin having structure A11 is produced from primary alcohol of corresponding to the hydrocarbon terpene (e.g., farnesol in the case of farnesene, or geraniol in the case of myrcene). The methods comprise hydrogenating the primary alcohol, forming a carboxylic acid ester or carbamate ester from the hydrogenated alcohol, and pyrolizing the ester (or heating the ester to drive the elimination reaction) to form the alpha-olefin with a saturated hydrocarbon tail, e.g., as described in Smith, L. E.; Rouault, G. F., J. Am. Chem. Soc. 1943, 65, 745-750, for the preparation of 3,7-dimethyloctene, which is incorporated by reference herein in its entirety. The primary alcohol of the corresponding hydrocarbon terpene may be obtained using any suitable method.

Alpha-olefins having the general structure A11 from conjugated hydrocarbon terpenes may be prepared via other schemes. For example, in some variations, the hydrocarbon terpene has a conjugated diene at the 1,3-position, and the conjugated diene can be functionalized with any suitable protecting group known to one of skill in the art in a first step (which may comprise one reaction or more than one reaction). The remaining olefinic bonds can be saturated in a second step (which may comprise one reaction or more than one reaction), and the protecting group can be eliminated to produce an alpha-olefin having the general structure A11 in a third step (which may comprise one reaction or more than one reaction).

Any suitable protecting group and elimination scheme may be used. For example, a hydrocarbon terpene having a 1,3-conjugated diene (e.g., β-farnesene) may be reacted with an amine (e.g., a dialkyl amine such as dimethylamine or diethylamine) in the first step to produce an amine having the formula N(R₁)(R₂)(R₃), where R₁ and R₂ are alkyl groups such as methyl or ethyl, and R₃ is an unsaturated hydrocarbon originating from the conjugated terpene. In the case of β-farnesene, R₃ is

The resulting amine may be oxidized to the N-oxide using hydrogen peroxide followed by elimination to the aldehyde using acetic anhydride. Hydrogenation of the aldehyde in the presence of a catalyst may be carried out to saturate any remaining olefinic bonds on the aliphatic tail originating from the hydrocarbon terpene, and the aldehyde functionality may be eliminated to produce an alpha-olefin having structure A11. Scheme I below illustrates an example of such a preparation of an alpha-olefin having structure A11 using β-farnesene as a model compound.

Another variation of a method to make an alpha-olefin from a hydrocarbon terpene having a 1,3-conjugated diene follows Scheme II below. Here, the hydrocarbon terpene is reacted with a dialkyl amine (e.g., dimethylamine). The resulting amine has the general formula N(R₁)₂(R₂), where R₁ and R₂ are alkyl groups such as methyl and R₃ is an unsaturated hydrocarbon originating from the hydrocarbon terpene (e.g., in the case of β-farnesene, R₃ is

The amine N(R₁)(R₂)(R₃) can be hydrogenated (e.g., using an appropriate catalyst), treated with peroxide, and heated to undergo elimination to form an alpha-olefin having structure A11 (e.g., compound A12 if β-farnesene is used as the starting hydrocarbon terpene). Scheme II illustrates this method using β-farnesene as a model compound.

In another variation, a hydrogenated primary alcohol corresponding to a hydrocarbon terpene (e.g., hydrogenated farnesol or hydrogenated geraniol) can be dehydrated using basic aluminum oxide (e.g., at a temperature of about 250° C.) to make an alpha-olefin having the general structure A11. Any suitable dehydration apparatus can be used, but in some variations, a hot tube reactor (e.g., at 250° C.) is used to carry out a dehydration of a primary alcohol. In one variation, hydrogenated farnesol can be dehydrated using basic aluminum oxide (e.g., in a hot tube reactor at 250° C.) to make compound A12, or an isomer thereof.

Other examples of particular species of partially hydrogenated conjugated hydrocarbon terpene that may have utility as a feedstock are mono-olefins having a saturated hydrocarbon tail with structure (A13) or structure (A15):

where n=1, 2, 3, or 4. A mono-olefin having the general structure A13, A15 or A11 may in certain instances be derived from a conjugated hydrocarbon terpene having a 1,3-diene moiety, such as myrcene, farnesene, springene, geranylfarnesene, neophytadiene, trans-phyta-1,3-diene, or cis-phyta-1,3-diene. Here again, the conjugated may be functionalized with a protecting group (e.g., via a Diels-Alder reaction) in a first step, exocyclic olefinic bonds hydrogenated in a second step, and the protecting group eliminated in a third step. In one non-limiting example of a method for making mono-olefins having the structure A13, A15 or A11, a conjugated hydrocarbon terpene having a 1,3-diene is reacted with SO₂ in the presence of a catalyst to form a Diels-Alder adduct. The Diels-Alder adduct may be hydrogenated with an appropriate hydrogenation catalyst to saturate exocyclic olefinic bonds. A retro Diels-Alder reaction may be carried out on hydrogenated adduct (e.g., by heating, and in some instances in the presence of an appropriate catalyst) to eliminate the sulfone to form a 1,3-diene. The 1,3-diene can then be selectively hydrogenated using a catalyst known in the art to result in a mono-olefin having structure A11, A13 or A15, or a mixture of two or more of the foregoing. Non-limiting examples of regioselective hydrogenation catalysts for 1,3-dienes are provided in Jong Tae Lee et al, “Regioselective hydrogenation of conjugated dienes catalyzed by hydridopentacyanocobaltate anion using β-cyclodextrin as the phase transfer agent and lanthanide halides as promoters,” J. Org. Chem., 1990, 55 (6), pp. 1854-1856, in V. M. Frolov et al, “Highly active supported palladium catalysts for selective hydrogenation of conjugated dienes into olefins,” Reaction Kinetics and Catalysis Letters, 1984, Volume 25, Numbers 3-4, pp. 319-322, in Tungler, A., Hegedus, L., Fodor, K., Farkas, G., Furcht, A. and Karancsi, Z. P. (2003) “Reduction of Dienes and Polyenes,” in The Chemistry of Dienes and Polyenes, Volume 2 (ed. Z. Rappoport), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/0470857226.chl2, and in Tungler, A., Hegedus, L., Fodor, K., Farkas, G., Furcht, A. and Karancsi, Z. P., “Reduction of Dienes and Polyenes” in Patai's Chemistry of Functional Groups (John Wiley and Sons, Ltd, published online Dec. 15, 2009, DOI: 10.1002/9780470682531.pat0233), each of which is incorporated herein by reference in its entirety. For example, a catalyst known in the art for 1,4 hydrogen addition to 1,3-dienes results in a mono-olefin having structure A13. In one non-limiting example, β-farnesene can be reacted with SO₂ in the presence of a catalyst to form a Diels-Alder adduct, which is subsequently hydrogenated, and the sulfone eliminated to form a 1,3-diene, which is subsequently selectively hydrogenated using a catalyst known in the art for regioselective hydrogen additions to 1,3-dienes to form 3,7,1 l-trimethyldodec-2-ene, 3,7,11-trimethyldodec-1-ene, or 3-methylene-7,11-dimethyldodecane, or a mixture of any two or more of the foregoing.

In yet another example of a particular species of partially hydrogenated hydrocarbon terpene that may have utility as a feedstock, a terminal olefin of the general structure A14 may be made from a conjugated hydrocarbon terpene having a 1,3-conjugated diene and at least one additional olefinic bond (e.g., myrcene, farnesene, springene, or geranylfarnesene):

where n=1, 2, 3, or 4. In one non-limiting variation, a compound having the structure A14 may be derived from an unsaturated primary alcohol corresponding to the relevant hydrocarbon terpene (e.g., farnesol in the case of farnesene, or geraniol in the case of myrcene). The unsaturated primary alcohol may be exposed to a suitable catalyst under suitable reaction conditions to dehydrate the primary alcohol to form the terminal olefin A14.

In one non-limiting example, a stoichiometric deoxygenation-reduction reaction may be conducted to form compounds having structure A14 from a primary alcohol (e.g., farnesol or geraniol) of a hydrocarbon terpene. One prophetic example of such a reaction can be conducted according to a procedure described in Dieguez et al, “Weakening C-0 Bonds: Ti(III), a New Reagent for Alcohol Deoxygenation and Carbonyl Coupling Olefination,” J. Am. Chem. Soc. 2010, vol. 132, pp. 254-259, which is incorporated by reference herein in its entirety: A mixture of titanocene dichloride (η⁵-C₅H₅)₂TiCl₂ (Cp₂TiCl₂) (3.88 mmol) and Mn dust (2.77 mmol) in strictly deoxygenated tetrahydrofuran (THF) (7 mL) can be heated at reflux under stirring until the red solution turns green. Then, to this mixture can be added a solution of the primary alcohol (e.g., farnesol or geraniol) (1.85 mmol) in strictly deoxygenated THF (4 mL). After the starting materials disappear, the reaction can be quenched with 1N HCl and extracted with tert-butylmethyl ether (t-BuOMe). The organic phase can be washed with brine, filtered and concentrated in vacuo to yield a crude product, which can be purified, e.g., by column chromatography (hexane/t-BuOMe, 8:1) over silica gel column to afford a compound having structure A14 (e.g., 3,7,11-trimethyldodeca-1,6,10-triene if farnesol is used as the starting material).

Other reactions may be conducted to form compounds having structure A14 from a primary alcohol (e.g., farnesol or geraniol) of a hydrocarbon terpene. One prophetic example of such a reaction can be conducted according to another procedure described in Dieguez et al, “Weakening C-0 Bonds: Ti(III), a New Reagent for Alcohol Deoxygenation and Carbonyl Coupling Olefination,” J. Am. Chem. Soc. 2010, vol. 132, pp. 254-259, which is incorporated herein by reference in its entirety: A mixture of Cp₂TiCl₂ (0.639 mmol) and Mn dust (17.04 mmol) in thoroughly deoxygenated THF (8 mL) and under Ar atmosphere can be stirred until the red solution turned green. This mixture may then be heated at reflux and the corresponding trimethylsilylchloride (TMSCI) (8.52 mmol) may be added. The primary alcohol (e.g., farnesol) (1.92 mmol) in strictly deoxygenated THF (2 mL) may then be added. After the starting materials disappear, the reaction may be quenched with t-BuOMe, washed with 1 N HCl, brine, dried, and concentrated under reduced pressure. The resulting crude may be purified, e.g., by column chromatography (hexane/t-BuOMe, 8:1) on silica gel to afford compound having structure A14 (e.g., 3,7,11-trimethyldodeca-1,6,10-triene if farnesol is used as the starting material).

An olefinic feedstock as described herein may comprise any useful amount of the particular species (e.g., alpha-olefinic species having structure A11, A12 or A15, mono-olefinic species having structure A13, or unsaturated terminal olefin species having structure A14), made either by a partial hydrogenation route or by another route, e.g., as described herein. In certain variations, an olefinic feedstock comprises at least about 1%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% species having structure A11, A12, A13, A14, or A15. In certain variations, an olefinic feedstock comprises at least about 1%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% 3,7,11-trimethyldodec-1-ene. In certain variations, an olefinic feedstock comprises at least about 1%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% 3-methylene-7,11-dimethyldodecane. In certain variations, an olefinic feedstock comprises at least about 1%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% 3,7,11-trimethyldodec-2-ene. In certain variations, an olefinic feedstock comprises at least about 1%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% 3,7,11-trimethyldodeca-1,6,10-triene. In certain variations, an olefinic feedstock comprises at least about 1%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% 3,7-dimethyloct-1-ene. In certain variations, an olefinic feedstock comprises at least about 1%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% 3,7-dimethyloct-2-ene. In certain variations, an olefinic feedstock comprises at least about 1%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% 3,7-dimethylocta-1,6-diene.

As described herein, in some variations, the hydrocarbon terpene feedstock comprising alpha-olefinic species or internal olefinic species of partially hydrogenated hydrocarbon terpenes are suitable for catalytic reaction with one or more alpha-olefins to form a mixture of isoparaffins comprising adducts of the terpene and the one or more alpha-olefins. In some variations, at least a portion of the mixture of isoparaffins so produced may be used as a base oil.

The performance advantages of synthetic hydraulic fluids made with biobased base oils of this disclosure, including for non-limiting examples embodiments employing biobased hydrocarbon base oils, changes the overall concept of hydraulic fluid performance. With the present disclosure, high performance can be obtained while still providing environmental compatibility.

The hydraulic fluids of this disclosure provide a number of advantages. In some embodiments, they are more biodegradable and have significantly more renewable content than poly-alpha-olefin (PAO) or mineral oil hydraulic fluids. In some embodiments, they have lower toxicity than Group I base oil hydraulic fluids. In some embodiments, they also demonstrate better hydrolytic stability and oxidation resistance than ester or vegetable oil hydraulic fluids. In some embodiments, the hydraulic fluids of this disclosure also have better demulsibility than esters/vegetable oil hydraulic fluids and also than some mineral oil based hydraulic fluids. Additionally, in some embodiments the hydraulic fluids of this disclosure provide better seal compatibility than vegetable or ester derived hydraulic fluids.

Table IV provides a comparison of one exemplary embodiment of a hydraulic fluid of this disclosure with various lubricants used commercially as hydraulic fluids. Table IV demonstrates that this exemplary embodiment of a renewable hydrocarbon hydraulic fluid (called the “experimental fluid”) provides “best in class” performance. This exemplary embodiment of a renewable hydrocarbon hydraulic fluid meets the most stringent environmental characteristics of renewability and biodegradability while demonstrating stability that is equal to or better than the industry leading petroleum products. That is, the exemplary fluid of this disclosure—the experimental fluid reported in Table IV showed Renewable Content >50% and Biodegradability >60% while meeting the wet TOST test requirements and providing outstanding oxidative stability. The PAO and mineral oil reported in Table IV both provided the classical performance as expected around wet TOST and oxidative stability but did not meet the environmental specifications. The ester materials met one or both of the renewability and biodegradability specifications but fell short when other performance areas were measured such as pour point, oxidation stability, and hydrolytic stability through the wet TOST test. The exemplary fluid of this disclosure also shows significantly improved oxidation stability than any of the commercial products.

TABLE IV Commercial Hydraulic Fluid Comparison With Example Fluid of Disclosure Experimental A B C D E Basestock Fluid 1 MINERAL PAO PAO SYN. ESTER VEG. OIL Ashless Yes No No No Yes Yes KV 40 cSt  43 46  46  48   45.9   36.8 VI 130 97 154 192 200 212 Pour Point ° C. −40 −33  −54 −47 −33 −34 Renewable Yes No No No Yes Yes Content >50% OECD 301B Yes No No No Yes Yes Biodegradability >60% Copper Strip 1B 1A 1B 1A 1A — Foam 50/0 20/0 50/0 0/0/0 0/10/0 — RPVOT  900+ 152  209 376 258  44 Minutes Wet TOST Yes Yes Yes Yes No No

Generally, a hydraulic fluid has a number of desirable characteristics. Among these is appropriate viscosity. Viscosity is a measure of a fluid's resistance to flow and is often a hydraulic fluid's most important characteristic. Viscosity significantly impacts operation of the system which a hydraulic fluid is to lubricate. When a hydraulic fluid has a viscosity that is too low, it does not seal sufficiently, leading to leakage and wear of parts, and the fluid also will not pump efficiently. When a hydraulic fluid has a viscosity that is too high, it can be difficult to pump through the system and may consequently reduce operating efficiency. Hydraulic fluids also preferably retain optimum viscosity during operation in cold or hot temperatures, in order to consistently and effectively transmit power. Historically, environmentally-friendly hydraulic oils have had trouble in cold temperature operation due to the triglyceride molecules in vegetable oil products having poor low temperature viscometric properties. Table IV shows that you can have a hydraulic fluid with environmentally friendly performance that can meet the pour point performance of the leading petroleum derived base oils.

The common measure of a fluid's ability to maintain viscosity through use in a hydraulic system is through Shear Stability testing. There are a number of Shear tests in industry but the KRL test is the most severe. As the use temperature for a hydraulic fluid changes, the viscosity of the fluid changes along with it. The fluid's ability to maintain viscosity as temperature changes is known as the Viscosity Index or VI. In a hydraulic formulation the base oil provides the base line for the final formulation VI and this is often enhanced with a VI improver. The goal is for the hydraulic fluid to have as high a VI as possible but be resistant to shear to maintain stable performance in the system. The biobased base oil of the current disclosure starts out with a high VI so little or no VI Improver is necessary to provide a high performing hydraulic fluid to market. Generally if the hydraulic fluid has a VI>130, then it can be considered a multi-grade hydraulic oil. This multigrade designation means that the hydraulic fluid can provide efficient performance across a wide temperature range and has performance advantages in both high and low temperature operation. VI is determined according to ASTM method D 2270-10e1. VI is related to kinematic viscosities measured at 40° C. and 100° C. using ASTM Method D 445-12.

Table V shows the shear stability of the biobased base oils in a fully formulated hydraulic oil. Formulation A contains no VI improver and has a VI of 130 for the formulation. This formulation has 0 shear loss in the KRL at 20 hours since there is no polymer present. Formulation B contains 9.5% of VI improver A and the effect on the formulation viscometrics is large. The VI jumps from 130 to 161 but the shear stability goes from 0 to 17% at 100° C. and 0 to 14.8% at 40° C. The Denison specification for KRL shear stability is 15% loss at 20 hours so the VI improver loading in formulation B would need to be slightly lowered to meet this specification.

TABLE V Formulation A Formulation B VI Improver A % 0 9.5 Add Pack % 0.75 0.87 Ester A % 10 25 Biobased Base Oil % 89.3 64.63 KRL 20 hr Results KV100 mm²/s 7.07 7.79 KV40 mm²/s 42.1 41.4 VI 130 161 % Loss 100′C % 0 17 % Loss 40′C % 0 14.8

Seal performance is critical to a hydraulic system to contain leaks and maintain performance. Base oil chemistry is a key driver for seal performance and the biobased base oils of this disclosure demonstrate equivalent or better performance than the conventional hydrocarbon alternatives. Table VI shows a comparison of the biobased base oil of this disclosure in comparison to a PAO with a mix of various ester chemistries. The PAO and the biobased base oil show equivalent seal performance. This is an advantage over typical biobased base oils that have high polarity and can offer induce significant seal swelling.

TABLE VI Seal Swell Testing Hydraulic Formulations: Biobased base oil vs PAO constaining Ester Formulations Parker Hydraulic Fluid Seal Material Nitrile N674-70, 7 days 100° C. Formulation Component wt % wt % wt % wt % wt % wt % wt % wt % wt % wt % wt % wt % Spectrasyn 4 99 95 90 90 90 90 Novaspec 450 99 95 90 90 90 90 PrioLube 3967 1 5 10 1 5 10 Esterex A32 10 10 Priolube 3970 10 10 Perfad 5000 10 10 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% Δ Seal Volume −5.6 −5.6 −5.7 −5.1 −5.1 −4.9 −3.3 −4.3 0.35 −2.7 −4.3 0.94 Δ Seal Hardness 3 4 4 3 3 3 3 2 0 1 2 0

In one embodiment, the hydraulic fluid compositions of the present disclosure comprise a biobased base oil and one or more additives constituting an “additive package” for the hydraulic fluid formulation. Thus, for example, the additive package may comprise one or more of the following additives (or a combination of additives from one class, e.g., a combination of anti-oxidants) in the following ranges (as a weight percentage of the hydraulic fluid formulation).

Antioxidants

Oxidation stability is a hydraulic fluid's resistance to heat-induced degradation caused by a chemical reaction with oxygen. Hydraulic fluids should preferably resist oxidation. Additives often help the fluid with this goal, improving the stability and extending the life of the fluid.

In one embodiment, the hydraulic fluid formulation comprises an anti-oxidant. For example, in one such embodiment the hydraulic fluid formulation will comprise about 0.01-5% anti-oxidant. By way of further example, in one such embodiment, the hydraulic fluid may comprise about 0.05-2% anti-oxidant. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.1-1% anti-oxidant. In each of these embodiments, the anti-oxidant may be a single anti-oxidant or it may comprise a combination of anti-oxidants. Further, in each of these embodiments, the anti-oxidant(s) may be selected from among phenolic, aminic, sulfur/phosphorous anti-oxidants or combinations thereof.

Antioxidants are typically free-radical traps, acting as free-radical reaction chain breakers. That is, effective antioxidants may be selected from radical scavengers such as phenolic, aminic antioxidants, or synergistic mixtures of these. For example, sulfurized phenolic antioxidants and organic phosphites are useful as components of such mixtures. Many antioxidant additives that are known and used in the formulation of lubricant products are suitable for use with the hydraulic fluid formulation described in this disclosure. Examples from one class of suitable antioxidants include without limitation butylated hydroxyanisole, di-butyl-paracresol (BHT), alkylated diphenylamines, tocopherol (vitamin-E), β-carotene, sterically hindered alkylthiomethylphenol, 2-(1,1-Dimethylethyl)-1,4-benzenediol, 1,2-dihydro-2,2,4-trimethylquinoline, ascorbyl palmitate, propyl gallate, and mixtures of these. In embodiments of this disclosure, such an antioxidant in an amount of 0.01 wt %˜2 wt % of the hydraulic oil may part of the additive package and be added to the biobased base oil. Hydraulic fluid for an application in the environmentally sensitive areas requires environmental performance of toxicity and biodegradability in addition to improved oxidation stability requirement. Some of the above listed chemistries can meet both requirements along with thiodiethylene bis (3,5-di-tert-butyl-4-hydroxyhydrocinnamate). This chemistry is a sterically hindered phenolic antioxidant. This chemistry is excellent for inhibiting oxidation and increasing thermal stability for hydrocarbon base oils. The preferred chemistry has low toxicity to aquatic fish and plants making it ideal for environmental applications.

Other types of phenolic anti-oxidants are available. Here the chemistry preferably contains no (or at least no detectible) or minimal levels of sulfur or phosphorus, to meet toxicity specifications for the formulation. This can allow the treat rate to be larger, up to 5%, preferably <2%, more preferable, <1%. These types of anti-oxidants can be in liquid form and this is the preferred state for ease of manufacturing. Further, octylated/butylated diphenylamine or alkylated phenyl-α-naphthylamine chemistry can be used. This aminic chemistry can be used alone or in combination with the phenolic anti-oxidants for synergistic effects. Depending on the type of amine chemistry the toxicity effects on the overall formulation may vary. For diphenylamine chemistry the treat rate may be <0.5% versus the naphthylamine which can treat at higher rates and up to 5%. Each of these chemistries contain nitrogen at levels <5% but contain no Sulfur or Phosphorous compounds.

Examples of phenolic antioxidants include 2,6-di-tert-butylphenol, liquid mixtures of tertiary butylated phenols, 2,6-di-tert-butyl-4-methylphenol, 4,4′-methylenebis(2,6-di-tert-butylphenol), 2,2′-methylenebis(4-methyl6-tert-butylphenol), mixed methylene-bridged polyalkyl phenols, 4,4′-thiobis(2-methyl-6-tert-butylphenol), 4,4′-butylidene-bis(3-methyl-6-tert-butylphenol), 4,4′-isopropylidene-bis(2,6-di-tert-butylphenol), 2,2′-methylene-bis(4-methyl-6-nonylphenol), 2,2′-isobutylidene-bis(4,6-dimethylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butyl-phenol, 2,6-di-tert-1-dimethylamino-p-cresol, 2,6-di-tert-4-(N,N′-dimethylaminomethylphenol), 4,4′-thiobis(2-methyl-6-tert-butylphenol), 2,2′-thiobis(4-methyl-6-tert-butylphenol), bis(3-methyl-4-hydroxy-5-tert-10-butylbenzyl)-sulfide, bis(3,5-di-tert-butyl-4-hydroxybenzyl), 2,2′-5-methylene-bis(4-methyl-6-cyclohexylphenol), N,N′-di-sec-butylphenylenediamine, 4-isopropylaminodiphenylamine, phenyl-α-naphthyl amine, phenyl-α-naphthyl amine, and ring-alkylated diphenylamines. Examples include the sterically hindered tertiary butylated phenols, bisphenols and cinnamic acid derivatives and combinations thereof. In yet another embodiment, the antioxidant is an organic phosphonate having at least one direct carbon-to-phosphorus linkage. Diphenylamine-type oxidation inhibitors include, but are not limited to, alkylated diphenylamine, phenyl-α-naphthylamine, and alkylated-α-naphthylamine. Other types of oxidation inhibitors include metal dithiocarbamate (e.g., zinc dithiocarbamate), and 15-methylenebis(dibutyldithiocarbamate). In another embodiment, class of antioxidants suitable for food grade industrial lubricant formulation are also useful in the hydraulic fluid described in the current disclosure. Examples of such antioxidants include, without limitation, butylated hydroxyanisole (BHA), di-butyl-paracresol (BHT), phenyl-a-naphthylamine (PANA), octylated/butylated diphenylamine, tocopherol (vitamin-E), β-carotene, sterically hindered alkylthiomethylphenol, 2-(1,1-Dimethylethyl)-1,4-benzenediol, 1,2-dihydro-2,2,4-trimethylquinoline, ascorbyl palm itate, propyl gallate, high molecular weight phenolic antioxidants, hindered bis-phenolic antioxidant, and mixtures of these.

In certain embodiments, exemplary phenolic anti-oxidants include: 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-di-t-butyl-4-heptyl phenol; and 2-methyl-6-di-t-butyl-4-dodecyl phenol. Examples of ortho coupled phenols include: 2,2′-bis(6t-butyl-4-heptyl phenol); 2,2′-bis(6-t-butyl-4-octyl phenol); and 2,2′-bis(6-t-butyl-4-dodecyl phenol). Sulfur containing phenolics may also be used to advantage in certain embodiments. The sulfur can be present as either aromatic or aliphatic sulfur within the phenolic antioxidant molecule. 4,4′-methylenebis(6-tert-butyl o-cresol), 4,4′-methylenebis(2-tert-amyl-o-cresol); 2,2′-methylenebis(4-methyl-6-tert-butylphenol); 4,4′-methylene-bis(2,6-di-tertbutylphenol.

In certain embodiments, exemplary aminic anti-oxidants include p,p′-dihexyldiphenylamine; p,p′-diheptyldiphenylamine; p,p′-dioctyldiphenylamine; p,p′-dinonyldiphenylamine; p,p′-didecyldiphenylamine; p,p′-didodecyldiphenylamine; octylphenyl-β-naphthylamine; t-octylphenyl-α-naphthylamine; phenyl-α-naphthylamine; phenyl-β-naphthylamine; p-octyl phenyl-α-naphthylamine; 4-octylphenyl-l-octyl-β-naphthylamine.

In certain embodiments, exemplary sulfur/phosphorous anti-oxidants include n-dodecyl-2-hydroxyethyl sulphide; 1-(tert-dodecylthio)-2-propanol; dibenzyl sulfide, polysulfides, diaryl sulfides, modified thiols, mercaptobenzimidazoles, thiophene derivatives, xanthogenates, and thioglycols, 2-(4-hydroxy-3,5-di-t-butyl benzyl thiol)acetate, alkylthiocarbamoyl with linear and branched alkyl groups of from 3-30 carbon atoms, alkyl and aryl mono, di, triphosphites with linear or branched alkyl or aryl group from 4-20 carbon atoms, thio and dithiophosphates with linear or branched alkyl or aryl groups from 4-20 carbons, neutralized as a metal salt such as zinc, molybdenum, antimony, bismuth or neutralized with an alkyl or aryl linear or branched amine with groups from 4-20 carbon.

Anti-Wear/Extreme Pressure

In one embodiment, the hydraulic fluid formulation comprises an anti-wear/extreme pressure additive. For example, in one such embodiment the hydraulic fluid formulation may comprise about 0.01-10% anti-wear/extreme pressure additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.01-2% anti-wear/extreme pressure additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.1-1% anti-wear/extreme pressure additive. In each of these embodiments, the anti-wear/extreme pressure additive may be a single anti-wear/extreme pressure additive or it may comprise a combination of anti-wear/extreme pressure additives. Further, in each of these embodiments, the anti-wear/extreme pressure additive may be selected from among the following compositions:

(i) mono-/di-butyl, hexyl, octyl, decyl, dodecyl, or fatty alcohol acid phosphate salts with long chain (C₁₁-C₁₄) alkylamines, fatty amines, ethoxylated amines, branched amines. Also aromatic phosphates such as cresyl diphenylphosphate;

(ii) zinc dialkyl dithiophosphate typically containing about 4 to about 12 carbon atoms and, more commonly about 6 to about 12 carbon atoms in each alkyl group. Preferably each alkyl group contains about 8 to about 12 carbon atoms. Examples of suitable alkyl moieties include butyl, sec-butyl, isobutyl, tert-butyl, pentyl, n-hexyl, sec-hexyl, n-octyl, 2-ethylhexyl, decyl and dodecyl;

(iii) alkyl and aryl mono, di, triphosphites with linear or branched alkyl or aryl group from 4-20 carbon atoms;

(iv) thio and dithiophosphates with linear or branched alkyl or aryl groups from 4-20 carbons, neutralized as a metal salt such as zinc, molybdenum, antimony, bismuth or neutralized with an alkyl or aryl linear or branched amine with groups from 4-20 carbon;

(v) triphenyl, butylated triphenyl, nonylated triphenyl phoshorothionates; and

(vi) sulfurized linear or branched olefins with 4-24 carbons.

Rust and Corrosion Inhibitors

A rust inhibitor is an additive that is mixed with a hydraulic fluid base oil to prevent rust in finished hydraulic fluid applications. Examples of commercial rust inhibitors are metal sulfonates, alkylamines, alkyl amine phosphates, alkenyl succinic acids, fatty acids, and acid phosphate esters. Rust inhibitors are sometimes comprised of one or more active ingredients. Examples of applications where rust inhibitors are needed include: internal combustion engines, turbines, electric and mechanical rotary machinery, hydraulic equipment, gears, and compressors. Rust inhibitors work by interacting with steel surfaces to form a surface film or neutralize acids. Rust inhibitors are effective in some embodiments of the hydraulic fluid when they are used in an amount less than 25 weight percent. In some other embodiments, rush inhibitors are effective in an amount less than 10 weight percent of the total composition. In some other embodiments, rust inhibitors are effective in an amount less than 1 weight percent, e.g., (less than 0.1%).

In one embodiment, the hydraulic fluid formulation comprises a rust or a corrosion inhibitor additive. For example, in one such embodiment the hydraulic fluid formulation may comprise about 0.01-5% rust and/or corrosion inhibitor additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.01-2% rust and/or corrosion inhibitor additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.1-0.5% rust and/or corrosion inhibitor additive. In each of these embodiments, the rust and/or corrosion inhibitor additive may be a single rust and/or corrosion inhibitor additive or it may comprise a combination of rust and/or corrosion inhibitor additives. Further, in each of these embodiments, the rust and/or corrosion inhibitor additive may be selected from among the following compositions:

(i) hydrocarbyl amine salts of alkylphosphoric acid, dihydrocarbyl amine salts of alkylphosphoric acid or hydrocarbyl amine salts of hydrocarbyl aryl sulphonic acid, especially reaction product of a C₁₄ to C₁₈ alkylated phosphoric acid with Primene 81 R (produced and sold by Rohm & Haas) which is a mixture of C₁₁ to C₁₄ tertiary alkyl primary amines;

(ii) succinimde derivatives such as the higher alkyl substituted amides of dodecylene succinic acid, higher alkyl substituted amides of dodecenyl succinic acid such as the tetrapropenylsuccinic monoesters (commercially available) and imidazoline succinic anhydride derivatives, e.g. the imidazoline derivatives of tetrapropenyl succinic anhydride;

(iii) alkenyl succinic acid half esters of mono or polyalcohols with linear or branch chain length of 3-30 carbons.

(iv) iso-nonyl phenoxy acetic acid;

(v) mono-/di-butyl, hexyl, octyl, decyl, dodecyl, or fatty alcohol acid phosphate salts with linear or branched chain from 4-20 carbons alkyl or aryl amines, fatty amines, ethoxylated amines, branched amines;

(vi) aromatic phosphates such as cresyl diphenylphosphate; and

(vii) imidazolines, sarcosine derivatives with linear or branched alkyl or aryl chain from 4-20 carbons.

Metal Deactivators

In one embodiment, the hydraulic fluid formulation comprises a metal deactivator additive. For example, in one such embodiment the hydraulic fluid formulation may comprise about 0.01-5% metal deactivator additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.01-2% metal deactivator additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.1-0.5% metal deactivator additive. In each of these embodiments, the metal deactivator additive may be a single metal deactivator additive or it may comprise a combination of metal deactivator additives. Further, in each of these embodiments, the rust and/or corrosion inhibitor additive may be selected from among the following compositions: N,N-disubstituted aminomethyl-1,2,4-triazoles, and the N,N-disubstituted amino methyl-benzotriazoles; derivatives of benzotriazoles, benzimidazole, 2-alkyldithiobenzimidazoles, 2-alkyldithiobenzothiazoles, 2-(N,N-dialkyldithio-carbamoyl)benzothiazoles, 2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles, 2,5-bis(N,N-dialkyidithiocarbamoyl)-1,3,4-thiadiazoles, and 2-alkyldithio-5-mercapto thiadiazoles.

Thickeners, VI Improvers and Pour Point Depressants

In one embodiment, the hydraulic fluid formulation comprises a thickener, viscosity index (“VI”) improver or pour point depressant additive. For example, in one such embodiment the hydraulic fluid formulation may comprise about 0.1-25% thickener, viscosity index (“VI”) improver or pour point depressant additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.5-20% thickener, viscosity index (“VI”) improver or pour point depressant additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 1-15% thickener, viscosity index (“VI”) improver or pour point depressant additive. In each of these embodiments, the thickener, viscosity index (“VI”) improver or pour point depressant additive may be a single thickener, viscosity index (“VI”) improver or pour point depressant additive or it may comprise a combination of thickener, viscosity index (“VI”) improver or pour point depressant additives. Further, in each of these embodiments, the thickener, viscosity index (“VI”) improver or pour point depressant additive may be selected from among the following compositions:

(i) polyisobutylenes, polymerized and co-polymerized alkyl methacrylates, and mixed esters of styrene maleic anhydride interpolymers reacted with nitrogen containing compounds. ethylene-propylene polymers, polymethacrylates and various diene block polymers and copolymers, polyolefins and polyalkylstyrenes, nitrogen-containing esters of carboxylic-containing interpolymers and the oil-soluble acrylate-polymerization products of acrylate esters, block copolymers produced by the anionic polymerization of unsaturated monomers including styrene, butadiene, and isoprene; and

(ii) esters of maleic anhydride-styrene copolymers, polymethacrylates; polyacrylates; polyacrylam ides; condensation products of haloparaffin waxes and aromatic compounds; vinyl carboxylate polymers; and terpolymers of dialkylfumarates, vinyl esters of fatty acids, ethylene-vinyl acetate copolymers, alkyl phenol formaldehyde condensation resins, alkyl vinyl ethers and mixtures thereof.

Esters and Co-Solvents

Esters can be considered a co-base oil or additive depending on the degree of environmental performance for the target of the formulation. Typically there can be a renewability requirement on the amount of renewable carbon contained in the overall formulation. The renewable base oil of the disclosure can vary in its amount of renewable carbon. To add additional renewable carbon fatty acids, esters, glycerine, or other biobased base oils can be considered. Some of these can be forms of Trimethylolpropantrioleates, Triglycerides, Trimethylolpropane esters, Polyl complex esters, 2-Ethylhexyl Cocoate, methyl esters, saturated trimethylolpropane ester, trimethylolpropane ester of carboxylic acids, saturated monopentaerythritol branched acids, trimethylolpropane, and complex esters of carboxylic acids.

In one embodiment, the hydraulic fluid formulation comprises an ester or cosolvent. For example, in one such embodiment the hydraulic fluid formulation may comprise about 0.1-75% ester or cosolvent. By way of further example, in one such embodiment the hydraulic fluid may comprise about 1-70% ester or cosolvent. By way of further example, in one such embodiment the hydraulic fluid may comprise about 3-20% ester or cosolvent. In each of these embodiments, the ester or cosolvent additive may be a single ester or cosolvent or it may comprise a combination of ester or cosolvent. Further, in each of these embodiments, the ester or cosolvent may be selected from among the following compositions (and included as a co-base oil or an additive):

-   -   (i) esters made by dehydration of mono-acids, di-acids,         tri-acids with alcohols with mono-, di- or multi-alcohols.         Preferred acids include C4-C30 monobasic acids, more preferably         2-ethylhexanoic acid, isoheptyl, isopentyl, and capric acids,         and di-basic acids, more preferably adipic, fumaric, sebacic,         azelaic, maleic, phthalic, and terephthalic acids, dimerized and         trimerized fatty acids. The alcohols can be any of the suitable         mono-alcohols or polyols. Preferred examples are glycerol,         2-ethylhexanol, iso-tridecanols, neopentyl glycol, trimethylol         ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylol propane,         pentaerythritol, and dipentaerythritol, ethoxylated,         propoxylated and butoxylated alcohols; and.     -   (ii) alkylbenzenes and other alkyl aromatics such as         alkylnaphthalenes.

Friction Modifiers

In one embodiment, the hydraulic fluid formulation comprises a friction modifier additive. For example, in one such embodiment the hydraulic fluid formulation may comprise about 0.01-5% friction modifier additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.05-5% friction modifier additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.1-2% friction modifier additive. In each of these embodiments, the friction modifier additive may be a single friction modifier additive or it may comprise a combination of friction modifier additives. Further, in each of these embodiments, the friction modifier additive may be selected from among the following compositions: aliphatic amines or ethoxylated aliphatic amines, aliphatic fatty acid amides, aliphatic carboxylic acids, aliphatic carboxylic esters, aliphatic carboxylic esteram ides, aliphatic phosphonates, aliphatic phosphates, aliphatic thiophosphonates, aliphatic thiophosphates, etc., wherein the aliphatic group usually contains above about eight carbon-atoms so as to render the compound suitably oil soluble. Also suitable are aliphatic substituted succinimides formed by reacting one or more aliphatic succinic acids or anhydrides with ammonia. Molybdenum salts such as carbamate, dithiocarbamate or dithiosphosphate.

Foam Inhibitors

In one embodiment, the hydraulic fluid formulation comprises a foam inhibitor additive. For example, in one such embodiment the hydraulic fluid formulation may comprise about 0.001-1% foam inhibitor additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.005-0.5% foam inhibitor additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.005-0.2% foam inhibitor additive. In each of these embodiments, the friction modifier additive may be a single foam inhibitor additive or it may comprise a combination of foam inhibitor additives. Further, in each of these embodiments, the foam inhibitor additive may be selected from among the following compositions: silicones, polyacrylates, surfactants

Demulsifiers

In one embodiment, the hydraulic fluid formulation comprises a demulsifier additive. For example, in one such embodiment the hydraulic fluid formulation may comprise about 0.001-1% demulsifier additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.005-0.5% demulsifier additive. By way of further example, in one such embodiment the hydraulic fluid may comprise about 0.005-0.2% demulsifier additive. In each of these embodiments, the demulsifier additive may be a single foam inhibitor additive or it may comprise a combination of demulsifier additives. Further, in each of these embodiments, the demulsifier additive may be selected from among the following compositions: derivatives of propylene oxide, ethylene oxide, polyoxyalkylene alcohols, alkyl amines, amino alcohols, diamines or polyamines reacted sequentially with ethylene oxide or substituted ethylene oxides or mixtures thereof. Examples of demulsifiers include trialkyl phosphates, polyethylene glycols, polyethylene oxides, polypropylene oxides, (ethylene oxide-propylene oxide) polymers and mixtures thereof.

Table VII shows that effect of different additive packages containing different anti-oxidant chemistries when varied by treat rate will impart large differences in the disclosures finished hydraulic fluid oxidation performance when measured by the RPVOT. In the test all of the disclosure formulas have the same base oil mixture of the biobased base oil of this disclosure in two different grades, 4 cSt and 6 cSt, along with an ester at 20%. There were 4 industry additive packages chosen from four different additive companies. The performance of the additive packages is compared at the recommended treat rate by the additive company and for Add Pack A and D the effect of treat rate was investigated. As expected as you increase the treat rate the oxidation performance is improved.

TABLE VII Formula 1 2 3 4 5 6 NovaSpec 450 16.62 16.54 16.54 16.62 16.80 16.70 NovaSpec 650 62.13 61.81 61.81 62.13 62.80 62.80 Ester A 20.00 20.00 20.00 20.00 20.00 20.00 Add Pack A 1.25 1.65 Add Pack B 1.65 Add Pack C 1.25 Add Pack D 0.40 0.50 RPVOT (min) 802 ± 96 850 ± 102 2595 ± 311 1206 ± 145 648 ± 78 692 ± 83 Commercial Hydraulic Oil Oxidation Performance to Exemplary Base Oil of the Present Disclosure Base Oil RPVOT (min) Mineral Oil 237 Mineral Oil 152 Non-Tox Mineral Oil 327 PAO 209 PAO 377 Synthetic Ester 359 Vegetable Oil 44 Experimental Fluid 1 1206 Experimental Fluid 2 2595

Evaluation of the Experimental fluid with two different additive packages demonstrates superior performance to the industry available products using various convention base oil technologies. It is valuable to look at the significant performance difference between the current market leading biobased base oil, vegetable oil, and the huge performance improvement capable with the biobased base oil of the disclosure. This performance is obtained while maintaining the renewability and biodegradability performance of the formulation. The experimental fluids also best the petroleum derived mineral oil and PAO products by a large margin illustrating the capability of the disclosure to create a product of performance that is not currently capable with existing technologies.

Water can react with additives in hydraulic fluids forming oil insoluble material. These insoluble materials will usually precipitate and in doing so may block filters, valves and other components, resulting in decreased flow of the hydraulic fluid in the system. Blockage can eventually result in unplanned downtime. Hydraulic fluids are thus typically designed so they can be filtered without depletion of additives to the fluids. The hydraulic fluids of this disclosure typically show excellent filterability results due to the biobased base oil chemistry and achieve values of <100 sec when running the Denison Filterability test, TP02100. When tested with and without water the formulations of this disclosure achieve the results shown below in Table VIII.

TABLE VIII Filterability (TP02100) Time (sec) Filtration Time without Water 70.31 Filtration Time with 2% Water 88.25

In many systems, water can enter the system as condensation or contamination, and mix with the hydraulic oil. Water can cause rusting of hydraulic components. In addition, water can react with some additives to form chemical species which can be aggressive to metals. Hydraulic fluid formulations typically contain rust and corrosion inhibitors which prevent the interaction of water or other chemical species from attacking metal surfaces. Such inhibitors are known and commercially available, Non-limiting examples include calcium sulfonate, N-acyl sarcosine, copper deactivators, fatty acid alkanolam ides based on saturated or unsaturated fatty acids typically having 10 to 20 carbon atoms, alcohols typically having 2 to 14 carbon atoms, and aromatic monocarboxylic acids and aliphatic dicarboxylic acids typically having 10 to 12 carbon atoms,

When hydraulic fluids come into contact with water, the water can interact with the additive system of the hydraulic oil resulting in the formation of acids. Hydraulic fluids that lack hydrolytic stability hydrolyze in the presence of water to form oil insoluble inorganic salts. Such salts can block filters and valves inhibiting oil flow and resulting in hydraulic system failure. Properly formulated hydraulic fluids are designed to contain additives that are resistant to interactions with water, helping to extend the life of the equipment. One of the biggest culprits of environmentally friendly hydraulic oils comprising esters is that the esters are very susceptible to hydrolysis, especially when they are also biodegradable. This performance limitation is demonstrated in the HE specification for environmentally friendly hydraulic oils since the wet TOST test is not required for the oils to meet required specifications for use in hydraulic fluids. This wet TOST is a standard industry test that is a part of the requirements for most all general mineral and PAO based hydraulic oils for reliable operations in all conditions. This is one area in which the renewable hydrocarbon base oil of this disclosure is novel in that it is a hydrocarbon and provides typical outstanding hydrolytic stability but can simultaneously meet the biodegradability and renewability specifications for environmentally friendly hydraulic oils.

Tables IX, X and XI show the drastic effect that esters have on hydrolytic stability of a hydraulic oil. The biobased base oil was formulated with a 6 cSt grade along with a standard additive package, anti-foam agent, and viscosity index improver (“VII”) this base formulation was then mixed with an ester at 25%. Five esters were explored to look at their change in acid number effect when running the D2619 hydrolytic stability test. Four of the five ester chemistries resulted in acid numbers that were significantly higher than the passing specification, while the other was improved but still outside of the D2619-09 passing specification for Denison HF-0. Ester #1 which showed the best performance in the ASTM D2619-09 test (Table IX), was used in formulations A-F (Table X) and evaluated in accordance with ASTM D943-04a (2010)e1. NOVASPEC biobased base oil was combined with Ester #1 (10%) and two different additive packages in two formulations (Formulations A and B) and each formulation passed ASTM D943-04a(2010)e1 with a total acid number (“TAN”) value of less than 1 at 1,000 hours (Table XI).

TABLE IX Wt % Wt % Wt % Wt % Wt % Novaspec 68.61 68.61 68.61 68.61 68.61 Ester 1 25 Ester 2 25 Ester 3 25 Ester 4 25 Ester 5 25 Add Package 1.1 1.1 1.1 1.1 1.1 AntiFoam 0.02 0.02 0.02 0.02 0.02 VII 5.27 5.27 5.27 5.27 5.27 Acid Number Change 0.11 0.42 0.42 0.44 0.46 (mg KOH/g) Total Acidity of H₂O 0.7 0.7 0.7 0.7 1.7 (mg KOH)

TABLE X Formulation A Formulation B Formulation C Formulation D Formulation E Formulation F Novaspec 73.8 78.8 83.8 88.8 93.8 98.8 Ester 1 25 20 15 10 5 0 Add Package 1.2 1.2 1.2 1.2 1.2 1.2 100 100 100 100 100 100 D664 Acid Number Buffer Buffer Buffer Buffer Buffer Buffer Time (hours) endpoint endpoint endpoint endpoint endpoint endpoint 0 0.15 0.18 0.18 0.17 0.16 0.19 168 0.4 0.31 0.14 0.14 0.15 0.15 336 0.98 0.71 0.7 0.15 0.43 0.48 504 1.77 1.61 0.99 0.5 0.38 0.17 672 2.69 1.65 1.18 0.63 0.18 0.23 840 2.85 1.66 0.75 0.33 0.16 1008 2.21 0.73 0.46 0.44 1176 1.44 0.18 0.41 1344 1.55 0.43 0.06 1512 1.62 0.45 0.36 1680 1.92 0.25 0.07 1848 2.12 0.47 0.2 2016 0.34 0.19

TABLE XI Formula Formulation A Formulation B NovaSpec 89.30 89.40 Ester 1 10.00 10.00 Add Pack 0.70 0.60 Total 100.00 100.00 D664 Acid D664 Acid Time (hours) Number Number 0 0.13 0.1 168 0.05 0.05 336 0.05 0.05 504 0.17 0.15 672 0.1 0.1 840 0.31 0.31 1008 0.27 0.26 1176 0.38 0.27 1344 0.54 0.46

In addition to resisting water, hydraulic fluids should also resist foaming. Foam is compressible and has poor lubricating properties and thus can hinder operation of the hydraulic fluid and the system it is in. Foam results from air or other gases becoming entrained in the hydraulic fluid. Air enters a hydraulic system through the reservoir or through air leaks within the system. A hydraulic fluid under high pressure can contain a large volume of dissolved or dispersed air bubbles. When this fluid is depressurized, the air bubbles expand and produce foam. Foam inhibitors typically modify the surface tension on air bubbles so they more easily break up.

Foam tendency and stability are measured by ASTM D 892-12. ASTM D 892-12 measures the foaming characteristics of a hydraulic base oil at 24° C. and 93.5° C. It provides a means of empirically rating the foaming tendency and stability of the foam. The lubricating base oil, maintained at a temperature of 24° C., is blown with air at a constant rate for 5 minutes then allowed to settle for 10 minutes. The volume of foam, in ml, is measured at the end of both periods (Sequence I). The foaming tendency is provided by the first measurement, the foam stability by the second measurement. The test is repeated using a new portion of the lubricating base oil at 93.5° C. (Sequence II). For ASTM D 892-13 Sequence III the same sample is used from Sequence II, after the foam has collapsed and cooled to 24° C. The lubricating base oil is blown with dry air for 5 minutes, and then settled for 10 minutes. The foam tendency and stability are again measured, and reported in ml. A good quality hydraulic oil will generally have less than 100 ml foam tendency for each of Sequence I, II, and III; and zero ml foam stability for each of Sequence I, II, III; the lower the foam tendency of a lubricating base oil or hydraulic oil the better.

The disclosure will be further understood by reference to the following examples which are not to be construed as limiting. Those skilled in the art will appreciate that other and further embodiments are apparent and within the spirit and scope of the claims from the teachings of the examples taken with the accompanying specification.

Table XII below provides formulations of three example hydraulic fluids tested. It can be seen that the selection of the proper defoamer is critical to meeting the foaming requirements for the hydraulic oil. In the sample formulations, the Defoamer B and C did not yield satisfactory results while Defoamer A meets the hydraulic oil specification and demonstrates the performance of the biobased base oil.

TABLE XII Formulation A Formulation B Formulation C Biobased Base Oil % 89.2 89.2 89.2 Ester A 10 10 10 Add Pack A 0.75 0.75 0.75 Defoamer A 0.04 Defoamer B 0.04 Defoamer C 0.04 Foam Test 10/10/50 290/20/270 120/30/240

In formulating the hydraulic fluids of this disclosure, according to some embodiments of this disclosure, the hydraulic fluid composition comprises specially formulated additive packages to provide required durability and performance. Various characteristics, properties and components which contribute to such characteristics and properties are discussed below.

A rust inhibitor is an additive that is mixed with a hydraulic fluid base oil to prevent rust in finished hydraulic fluid applications. Examples of commercial rust inhibitors are metal sulfonates, alkylamines, alkyl amine phosphates, alkenyl succinic acids, fatty acids, and acid phosphate esters. Rust inhibitors are sometimes comprised of one or more active ingredients. Examples of applications where rust inhibitors are needed include: internal combustion engines, turbines, electric and mechanical rotary machinery, hydraulic equipment, gears, and compressors. Rust inhibitors work by interacting with steel surfaces to form a surface film or neutralize acids. Rust inhibitors are effective in some embodiments of the hydraulic fluid when they are used in an amount less than 25 weight percent. In some other embodiments, rush inhibitors are effective in an amount less than 10 weight percent of the total composition. In some other embodiments, rust inhibitors are effective in an amount less than 1 weight percent, e.g., (less than 0.1%).

Rust inhibition of lubricating oils or hydraulic oils is determined using ASTM D 665-12. ASTM D 665-12 is directed to a test for determining the ability of oil to aid in preventing the rusting of ferrous parts should water become mixed with the oil. In this test a mixture of 300 ml. of the test oil is stirred with 30 ml. of distilled or synthetic seawater at a temperature of 60° C. with a cylindrical steel specimen completely immersed therein for 4 hours, although longer and shorter periods of time also may be utilized.

Air release properties are generally associated with the base oil composition and kinematic viscosity. Air release properties are measured by ASTM D 3427-12.

The air release test is done by saturating the fluid (normally at 50° C., but other temperatures such as 25° C. are also possible) with air bubbles and then measuring the time it takes for the fluid to return to an air content of 0.2%. Air release times are generally longer for Group I base oils than for Group III base oils. Polyol ester, poly-alpha-olefin, and phosphate ester base oils typically have lower air release than conventional mineral oils. Typical air release specifications for hydraulic oils vary from 5 minutes maximum for ISO 32 oils, through 7 minutes maximum for ISO 46 oils, through 17 minutes maximum for ISO 150 oils. Air release values generally increase with viscosity of the base oil.

Good air release is a critical property for hydraulic fluids. Agitation of hydraulic fluid with air in equipment, such as bearings, couplings, gears, pumps, and oil return lines, may produce a dispersion of finely divided air bubbles in the oil. If the residence time in the hydraulic system reservoir is too short to allow the air bubbles to rise to the oil surface, a mixture of air and oil will circulate through the hydraulic system. This may result in an inability to maintain oil pressure, incomplete oil films in bearings and gears, and poor hydraulic system performance or failure. The inability to maintain oil pressure is especially pronounced with hydraulic systems having centrifugal pumps. Oil having poor air release can cause sponginess and lack of sensitivity of the control of turbine and hydraulic systems.

One of the most severe effects of a hydraulic oil having poor air release is pump cavitation. Cavitation of the hydraulic pump is evidenced primarily by increased pump noise and excessive pump vibration, and also by loss of high pressure in the hydraulic system or loss of speed in hydraulic system cylinders. When the hydraulic oil being pumped in a hydraulic system enters the pump inlet the pressure is significantly reduced. The greater the flow velocity through the pump the greater the pressure drop. If the pressure drop is high enough, and the hydraulic oil has poor air release, the air contained in the hydraulic oil is carried into the pump as small bubbles. As the hydraulic oil flow velocity decreases the fluid pressure increases, causing the air bubbles to suddenly collapse on the outer portions of the pump impeller. The formation of the air bubbles and their subsequent collapse is referred to as pump cavitation. The hydraulic pump may be seriously damaged by cavitation.

Air release is measured by ASTM D 3427-12. Compressed air is blown through the test oil, which has been heated to a temperature of 25 or 50° C. After the air flow is stopped, the time required for the air entrained in the oil to reduce in volume to 0.2% is recorded under the conditions of the test and at the specified temperature. Air release is mainly a function of the base stock, and oils need to be monitored for this. Additives cannot positively influence air release time. The air releases of the hydraulic fluids of the present disclosure are very low, generally less than 2.1 minutes at 50° C. as illustrated in Table XIII.

TABLE XIII Formula wt % Novaspec 450 7.79% Novaspec 650 81.51% Ester A 10.00% Add Package 0.70% 100.00% Air Release Time (min) Gas bubble 2.1 separation time at 50° C., min (ASTM D3427)

The anti-wear/extreme pressure additive may be an additive package provided by an additive company or formulated by a lubricant formulator. A preferred additive package is an AW hydraulic oil additive package, more preferably one that meets the Denison HF-0 standard. It may be an ashless, zinc-free, or a zinc-based AW hydraulic oil additive package. Preferred AW hydraulic oil additive packages designed to meet the Denison HF-0 standard will also meet the AFNOR wet filterability test. The Denison HF-0 standard concerns hydraulic oils for use in axial piston pumps and vane pumps in severe duty applications. In certain embodiments, the hydraulic fluids of the present disclosure utilize additives that can meet the Denison HFO standard along with strict environmental regulations like EcoLabel. The anti-wear additive is critical to the environmental performance because it typically contains chemistry that can be harmful for the environment. Amine phosphates (e.g., IRGALUBE® 349 (Ciba Specialty Chemicals) may be used as a way of providing anti-wear benefits along with environmentally acceptable chemistry in an anti-wear/extreme pressure and also supply some antirust activity. This type of additive can be utilized in a formulation up to 2.5% and more preferably at 1%, 0.1-0.5% and still meet the toxicity and performance requirements of the formulation. It is preferred that this additive chemistry has Nitrogen levels <5% more preferably <3%. Sulfur is a typical chemistry used in anti-wear/extreme pressure additives, this chemistry provides excellent performance where the environment is not concerned, but when looking for toxicity and biodegradability the sulfur levels should be 0% of the anti-wear/extreme pressure additive. Phosphorus is another common anti-wear/extreme pressure chemistry and the additive should have <5% to meet the environmental considerations. In addition this chemistry can be biodegradable benefiting the overall formulation performance. Triphenyl phosphorothionate, TPPT, another form of ashless anti-wear chemistry can be used alone or with the Amine Phosphates to provide superior overall protection. Unlike the Amine Phosphate the TPPT will contain sulfur and have higher levels of phosphorus, each typical >5%. The TPPT anti wear chemistry can only be used at treat rates up to 0.1% to meet the environmental specifications due to this chemistry. At these low treat levels there is minimal impact to the overall biodegradability of the formulation. Additionally butylated triphenyl phosphorothionate chemistry can be used at appropriate levels.

The HF-0 standard specifies high thermal stability, good rust prevention, high hydrolytic stability, good oxidation stability, low foaming, excellent filterability with and without water, and satisfactory performance in proprietary Denison pump tests. In addition the HF-0 standard specifies the hydraulic oil have a viscosity index greater than 90, and a minimum aniline point of 100° C. (212° F.).

Wet filterability may be measured by the Denison TP 02100 test method or the AFNOR NFE 48-691 standard. For example, only fluids passing AFNOR NFE 48-691 are specified for injection molding hydraulic oils. The latter test measures filtration in the presence of water for an aged oil, which more closely replicates actual operating conditions. The tests measure the times taken to filter initial and subsequent volumes of oil, which are then used to calculate the Index of Filtration (IF). The closer the IF is to one, the lower the tendency to clog filters over time and therefore the more desirable the oil.

The number of minutes to 3 ml emulsion at 54° C. is a measure of the demulsibility of the hydraulic oil. Demulsibility is measured by ASTM D 1401-12. A 40-ml sample of oil and 40 ml of distilled water are put into a 100-m1 graduate cylinder. The mixture is stirred for 5 minutes while maintained at a temperature of 130° F. The time required for separation of the emulsion into its oil and water components is recorded. If, at the end of 30 minutes, 3 or more milliliters of emulsion still remain, the test is discontinued and the milliliters of oil, water, and emulsion are reported. The 3 measurements are presented in that order and are separated by hyphens. Test time, in minutes, is shown in parenthesis.

Preferably the hydraulic oils of this disclosure will have excellent demulsibility. That is, the number of minutes to 3 ml emulsion at 54° C. by ASTM D 1401-12 is preferably less than 30 minutes, more preferably less than 20 minutes. One example formulation of the present disclosure yielded results shown in Table XIV.

TABLE XIV TEST HF-0 Test Results Demulsibility 40/37/3 (30 min) 40/40/0 (5 min)

While comparing degree of biodegradation of base oil using OECD 301B method can provide comparison of environmental performance of different types of base oil, the effect of the viscosity of the base oil on the degradation behavior should also be noted. For example, poly-alpha-olefin (PAO), classified as a Group IV base oil by The American Petroleum Institute (API), can achieve greater than 60% of biodegradation in 28 days when the base oil mainly consists of PAO with kinematic viscosity (at 40° C.) of about 5.1 cSt. However, PAO base oil can only achieve less than 35% of biodegradation in 28 days when its kinematic viscosity (at 40° C.) is greater than 31 cSt.

FIG. 1 compares biodegradability of different types of base oils using the OECD 301B method, which is considered to be part of the environmental performance matrix. In order to provide a fair comparison, base oils with similar kinematic viscosity are compared (31 cSt˜37 cSt at 40° C., noted in FIG. 1). Tests were extended to 40 days to prove long term behavior rather than the standard period of 28 days. Slightly greater than 10 days of lag phase was observed from the biodegradation of PAO. PAO showed 22% of biodegradation by 21 days and reached a plateau value, 27% biodegradation, by 25 days. Isoparaffinic base oil, classified as Group III base oil according to API classification, showed improved biodegradation behavior over PAO. For the isoparaffinic base oil, duration of the lag phase was less than 6 days, and the plateau value of 56% was reached by 25 days. In contrast, biobased hydrocarbon base oil showed 78% biodegradation at 28 days, and by 40 days, achieved 90% biodegradation and had not entered the plateau phase (FIG. 1, solid circle symbol).

FIG. 2 plots the results of percentage biodegradation of hydraulic oil formulated with biobased base oils according to one embodiment of the present disclosure, Exp-Hyd.BL.1, over a period of 28 days. Exp-Hyd.BL.1, comprised of biobased hydrocarbon base oils, showed about 65% biodegradation at 28 days. Considering that Exp-Hyd.BL.1 has much higher viscosity (46 cSt at 40° C., FIG. 2) than any base oils (about 32 cSt at 40° C.) shown in FIG. 1, yet Exp-Hyd.BL.1 achieved greater than 60% of biodegradation, the improvement in its biodegradability is evident.

The biobased base oils discussed in the test examples comprise a biobased hydrocarbon base oil However, it is contemplated that other biobased base oils, not necessarily hydrocarbon based, but synthesized to have favorable properties, would also have the benefits of the biobased hydrocarbon base oil hydraulic fluids. The foregoing examples demonstrate that the hydraulic fluids disclosed herein provide a hydraulic fluid that has superior or competitive properties to fluids previously available.

Also the disclosure provides an improved non-petroleum based, environmentally safe hydraulic fluid that can be commercially used in the hydraulic systems operated under widely varying conditions. The hydraulic fluid of the disclosure utilizes a renewable isoparaffinic base oil derived from terpenes. The hydraulic fluid of the disclosure has been designed to maintain a stable viscosity and have an improved pour point.

The present disclosure further includes the following enumerated embodiments.

Embodiment 1. A hydraulic fluid comprising a biobased hydrocarbon base oil having an average molecular weight (weight average) between 300 g/mol and 900 g/mol, and an additive package, the additive package comprising an anti-oxidant.

Embodiment 2. A hydraulic fluid comprising a biobased hydrocarbon base oil, the hydraulic fluid having a biodegradable rate in excess of 60% as determined in accordance with OECD 301B.

Embodiment 3. A hydraulic fluid comprising a biobased base oil having the molecular structure:

[B]_(n)—[P]_(m)

wherein,

-   -   [B] is biobased hydrocarbon repeating unit;     -   [P] is non-biobased hydrocarbon repeating unit;     -   n is greater than 1, and m is less than 4;     -   the stereoscopic arrangement of [B] and [P] repeating unit can         be linear, branched, and cyclic.     -   the sequential arrangement of [B] and [P] can be block,         alternating or random; and     -   the molecular weight is in range of 300 g/mol to 900 g/mol; and     -   the biobased content of the hydraulic fluid is greater than 20%,         as measured by ASTM D6866-12.

Embodiment 4. A hydraulic fluid comprising a biobased base oil, wherein at least about 20% of the carbon atoms in the biobased base oil originate from renewable carbon sources and the hydraulic fluid meets Denison Hydraulics standard HF-0.

Embodiment 5. A hydraulic fluid comprising a biobased base oil, wherein at least about 20% of the carbon atoms in the biobased base oil originate from renewable carbon sources and the hydraulic fluid has a TAN <2 at 1000 hours as determined in accordance with ASTM D943-04a (2010)e1.

Embodiment 6. A hydraulic fluid comprising a biobased hydrocarbon base oil, wherein at least about 20% of the carbon atoms in the biobased base oil originate from renewable carbon sources and the hydraulic fluid has a pour point of less than 40° C.

Embodiment 7. A hydraulic fluid comprising a biobased hydrocarbon base oil, the hydraulic fluid being compatible with and suitable for mixing with a Group I, Group II, or Group III hydraulic fluid.

Embodiment 8. A hydraulic fluid having an ISO viscosity grade of 2 to 46,000 and comprising:

(a) 1 to 95 wt % of a biobased hydrocarbon base oil containing carbon from a renewable source; and

(b)(i) 5 to 50 wt % of at least a first basestock selected from Group I base oils having a viscosity range of from 3 cSt to 50 cSt and combinations thereof, Group II and Group III hydroprocessed base oils and combinations thereof, and Group IV PAOs having a viscosity index of about 130 or less and combinations thereof; or

(b)(ii) 1 to 50 wt % of a second basestock selected from Group V base oils and combinations thereof.

Embodiment 9. The hydraulic fluid of embodiment 8 wherein the hydraulic fluid has an absence of any additional polymeric thickeners and viscosity index improvers.

Embodiment 10. The hydraulic fluid according to embodiment 8 or 9, wherein the biobased hydrocarbon base oil is characterized by a viscosity index (VI) greater than 160, as measured in accordance with ASTM D2270-10e1, and a branch ratio of less than 0.41.

Embodiment 11. The hydraulic fluid according to any of embodiments 8 to 10, wherein the hydraulic fluid contains about 2 to 25 wt % of the second basestock.

Embodiment 12. The hydraulic fluid according to any of embodiments 8 to 11, wherein the second basestock comprises a Group V base-stock selected from alkylated aromatics, polyalkylene glycols, esters, and mixtures thereof.

Embodiment 13. The hydraulic fluid according to any of embodiments 8 to 12, wherein the hydraulic fluid comprises 5 to 50 wt % of the first basestock and 1 to 50 wt % of the second basestock.

Embodiment 14. A hydraulic fluid comprising: (a) a base oil having a weight average molecular weight in the range of 400 to 600 g/mol, a viscosity index greater than 120 and less than 140; and (b) an anti-wear hydraulic oil additive package; wherein the hydraulic fluid has (i) an air release by ASTM D 3427-012 of less than 3 minutes at 50° C., and (ii) a Sequence II foam tendency by ASTM D 892-13 of less than 50 ml, and a biodegradability rate of at least 60% as determined by OECD 301B.

Embodiment 15. The hydraulic fluid of embodiment 14, wherein the base oil comprises carbon from a renewable source.

Embodiment 16. The hydraulic fluid of embodiment 14 or 15, wherein the base oil additionally has an average degree of branching in the molecules less than about 8 alkyl branches per 100 carbon atoms.

Embodiment 17. The hydraulic fluid of embodiment 14, 15 or 16, wherein the base oil comprises at least 5 weight percent molecules with monocycloparaffinic functionality.

Embodiment 18. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the base oil has a T90-T1-0 boiling range distribution of less than 180° F.

Embodiment 19. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the average molecular weight of the base oil is between about 500 and about 900 g/mol.

Embodiment 20. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the base oil has a Bromine Index <200.

Embodiment 21. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid has an air release at 50° C. of less than 2.1 minutes.

Embodiment 22. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid has an air release at 25° C. of less than 10 minutes.

Embodiment 23. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the base oil has an aniline point between 212 and 300° F.

Embodiment 24. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid has a Sequence I foam tendency as determined in accordance with ASTM D892-13 of less than 50 ml.

Embodiment 25. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid has a Sequence II foam tendency as determined in accordance with ASTM D 892-13 of less than 30 ml.

Embodiment 26. The hydraulic fluid any preceding enumerated embodiment, wherein the hydraulic fluid has a number of minutes to 3 ml emulsion at 54° C. as determined in accordance with ASTM D1401-12 of less than 30.

Embodiment 27. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid meets the Denison HF-0 hydraulic oil standard.

Embodiment 28. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid has an ISO viscosity grade of ISO 22, ISO 32, ISO 46, ISO 68, or ISO 100.

Embodiment 29. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the base oil has alkyl branches positioned over various branch carbon resonances as determined in accordance by carbon −13 NMR.

Embodiment 30. The hydraulic fluid of any of embodiments 1 to 29, wherein the hydraulic fluid has an FZG gear wear rating determined in accordance with ASTM D5182-97 (2014) in excess of 11.

Embodiment 31. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid is biodegradable.

Embodiment 32. The hydraulic fluid of any of embodiments 1 to 30 wherein the hydraulic fluid has a biodegradable rate in excess of 60% according to by OECD 301B.

Embodiment 33. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the base oil comprises a biobased terpene selected from the group consisting of myrcene, ocimene, farnesene, and combinations thereof.

Embodiment 34. The hydraulic fluid of any of preceding enumerated embodiment, wherein the hydraulic fluid comprises an additive package.

Embodiment 35. The hydraulic fluid of any of embodiments 1 to 33 wherein the hydraulic fluid comprises about 0.2 to about 2 wt % of an additive package.

Embodiment 36. The hydraulic fluid of any of embodiments 1 to 33 wherein the hydraulic fluid comprises about 50 wt % to about 99 wt % biobased hydrocarbon base oil and from about 0.2 to about 2 wt % additive package.

Embodiment 37. The hydraulic fluid of any of embodiments 34 to 36 wherein the additive package comprises at least one additive selected from the group consisting of anti-oxidants, anti-wear agents, extreme pressure agents, defoamants, detergent/dispersant, rust and corrosion inhibitors, and demulsifiers.

Embodiment 38. The hydraulic fluid of embodiment 37 wherein the additive package comprises an anti-wear additive selected from the group consisting of ashless, zinc-free, and zinc-containing anti-wear additives, and combinations thereof.

Embodiment 39. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the additive package is an ashless additive package.

Embodiment 40. The hydraulic fluid of any of embodiments 1 to 38 wherein the hydraulic fluid comprises less than 0.11 wt. % sulfated ash derived from the additive package.

Embodiment 41. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid contains between about 0.1 wt % and about 1 wt % of a phenolic anti-oxidant.

Embodiment 42. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid contains an anti-wear additive.

Embodiment 43. The hydraulic fluid of embodiment 42 wherein the anti-wear additive contains an amine phosphate anti-wear additive and the hydraulic fluid further comprises up to about 1 wt % of the anti-wear additive(s).

Embodiment 44. The hydraulic fluid of any of the preceding enumerated embodiments, wherein the hydraulic fluid contains a viscosity index improver.

Embodiment 45. The hydraulic fluid of embodiment 44 wherein the hydraulic fluid contains at least 1 wt % of the viscosity index improver.

Embodiment 46. In an apparatus comprising a pump lubricated by a hydraulic fluid, the improvement comprising a hydraulic fluid according to any of the preceding enumerated embodiments.

Embodiment 47. In a gear system, circulation lubrication system, hydraulic system, compressor system, vacuum pump, metal working machinery, electrical switch or connector comprising a hydraulic fluid, the improvement comprising a hydraulic fluid according to any preceding enumerated embodiment.

Various embodiments have been described. However, the present disclosure is not intended to be limited to these embodiments and illustrations contained herein. The disclosure includes modified forms of the described embodiments, including portions of the embodiments and combinations of elements of different embodiments. These and other embodiments are within the scope of the following claims. 

What is claimed is:
 1. A hydraulic fluid comprising a biobased hydrocarbon base oil having an average molecular weight (weight average) between 300 g/mol and 900 g/mol, and an additive package, the additive package comprising an anti-oxidant.
 2. A hydraulic fluid comprising a biobased hydrocarbon base oil, the hydraulic fluid having a biodegradable rate in excess of 60% as determined in accordance with OECD 301B.
 3. A hydraulic fluid comprising a biobased base oil having the molecular structure: [B]_(n)—[P]_(m) wherein, [B] is biobased hydrocarbon repeating unit; [P] is non-biobased hydrocarbon repeating unit; n is greater than 1, and m is less than 4; the stereoscopic arrangement of [B] and [P] repeating unit can be linear, branched, and cyclic. the sequential arrangement of [B] and [P] can be block, alternating or random; and the molecular weight is in range of 300 g/mol to 900 g/mol; and the biobased content of the hydraulic fluid is greater than 20%, as measured by ASTM D6866-12.
 4. A hydraulic fluid comprising a biobased base oil, wherein at least about 20% of the carbon atoms in the biobased base oil originate from renewable carbon sources and the hydraulic fluid meets Denison Hydraulics standard HF-0.
 5. A hydraulic fluid comprising a biobased base oil, wherein at least about 20% of the carbon atoms in the biobased base oil originate from renewable carbon sources and the hydraulic fluid has a TAN <2 at 1000 hours as determined in accordance with ASTM D943-04a (2010)e1.
 6. A hydraulic fluid comprising a biobased hydrocarbon base oil, wherein at least about 20% of the carbon atoms in the biobased base oil originate from renewable carbon sources and the hydraulic fluid has a pour point of less than 40° C.
 7. A hydraulic fluid comprising a biobased hydrocarbon base oil, the hydraulic fluid being compatible with and suitable for mixing with a Group I, Group II or Group III hydraulic fluid.
 8. A hydraulic fluid having an ISO viscosity grade of 2 to 46,000 and comprising: (a) 1 to 95 wt % of a biobased hydrocarbon base oil containing carbon from a renewable source; and (b)(i) 5 to 50 wt % of at least a first basestock selected from Group I base oils having a viscosity range of from 3 cSt to 50 cSt and combinations thereof, Group II and Group III hydroprocessed base oils and combinations thereof, and Group IV PAOs having a viscosity index of about 130 or less and combinations thereof; or (b)(ii) 1 to 50 wt % of a second basestock selected from Group V base oils and combinations thereof.
 9. The hydraulic fluid of claim 8 wherein the hydraulic fluid has an absence of any additional polymeric thickeners and viscosity index improvers.
 10. The hydraulic fluid according to claim 8 or 9, wherein the biobased hydrocarbon base oil is characterized by a viscosity index (VI) greater than 160, as measured in accordance with ASTM D2270-10e1, and a branch ratio of less than 0.41.
 11. The hydraulic fluid according to any of claims 8 to 10, wherein the hydraulic fluid contains about 2 to 25 wt % of the second basestock.
 12. The hydraulic fluid according to any of claims 8 to 11, wherein the second basestock comprises a Group V base-stock selected from alkylated aromatics, polyalkylene glycols, esters, and mixtures thereof.
 13. The hydraulic fluid according to any of claims 8 to 12, wherein the hydraulic fluid comprises 5 to 50 wt % of the first basestock and 1 to 50 wt % of the second basestock.
 14. A hydraulic fluid comprising: (a) a base oil having a weight average molecular weight in the range of 400 to 600 g/mol, a viscosity index greater than 120 and less than 140; and (b) an anti-wear hydraulic oil additive package; wherein the hydraulic fluid has (i) an air release by ASTM D 3427-012 of less than 3 minutes at 50° C., and (ii) a Sequence II foam tendency by ASTM D 892-13 of less than 50 ml, and a biodegradability rate of at least 60% as determined by OECD 301B.
 15. The hydraulic fluid of claim 14, wherein the base oil comprises carbon from a renewable source.
 16. The hydraulic fluid of claim 14 or 15, wherein the base oil additionally has an average degree of branching in the molecules less than about 8 alkyl branches per 100 carbon atoms.
 17. The hydraulic fluid of claim 14, 15 or 16, wherein the base oil comprises at least 5 weight percent molecules with monocycloparaffinic functionality.
 18. The hydraulic fluid of any preceding claim, wherein the base oil has a T90-T1-0 boiling range distribution of less than 180° F.
 19. The hydraulic fluid of any preceding claim, wherein the average molecular weight of the base oil is between about 500 and about 900 g/mol.
 20. The hydraulic fluid of any of any preceding claim, wherein the base oil has a Bromine Index <200.
 21. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid has an air release at 50° C. of less than 2.1 minutes.
 22. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid has an air release at 25° C. of less than 10 minutes.
 23. The hydraulic fluid of any preceding claim, wherein the base oil has an aniline point between 212 and 300° F.
 24. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid has a Sequence I foam tendency as determined in accordance with ASTM D892-13 of less than 50 ml.
 25. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid has a Sequence II foam tendency as determined in accordance with ASTM D 892-13 of less than 30 ml.
 26. The hydraulic fluid any preceding claim, wherein the hydraulic fluid has a number of minutes to 3 ml emulsion at 54° C. as determined in accordance with ASTM D1401-12 of less than
 30. 27. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid meets the Denison HF-0 hydraulic oil standard.
 28. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid has an ISO viscosity grade of ISO 22, ISO 32, ISO 46, ISO 68, or ISO
 100. 29. The hydraulic fluid of any preceding claim, wherein the base oil has alkyl branches positioned over various branch carbon resonances as determined in accordance by carbon −13 NMR.
 30. The hydraulic fluid of any of claims 1 to 29, wherein the hydraulic fluid has an FZG gear wear rating determined in accordance with ASTM D5182-97 (2014) in excess of
 11. 31. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid is biodegradable.
 32. The hydraulic fluid of any of claims 1 to 30 wherein the hydraulic fluid has a biodegradable rate in excess of 60% according to by OECD 301B.
 33. The hydraulic fluid of any preceding claim, wherein the base oil comprises a biobased terpene selected from the group consisting of myrcene, ocimene, farnesene, and combinations thereof.
 34. The hydraulic fluid of any of preceding claim, wherein the hydraulic fluid comprises an additive package.
 35. The hydraulic fluid of any of claims 1 to 33 wherein the hydraulic fluid comprises about 0.2 to about 2 wt % of an additive package.
 36. The hydraulic fluid of any of claims 1 to 33 wherein the hydraulic fluid comprises about 50 wt % to about 99 wt % biobased hydrocarbon base oil and from about 0.2 to about 2 wt % additive package.
 37. The hydraulic fluid of any of claims 34 to 36 wherein the additive package comprises at least one additive selected from the group consisting of anti-oxidants, anti-wear agents, extreme pressure agents, defoamants, detergent/dispersant, rust and corrosion inhibitors, and demulsifiers.
 38. The hydraulic fluid of claim 37 wherein the additive package comprises an anti-wear additive selected from the group consisting of ashless, zinc-free, and zinc-containing anti-wear additives, and combinations thereof.
 39. The hydraulic fluid of any preceding claim, wherein the additive package is an ashless additive package.
 40. The hydraulic fluid of any of claims 1 to 38 wherein the hydraulic fluid comprises less than 0.11 wt. % sulfated ash derived from the additive package.
 41. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid contains between about 0.1 wt % and about 1 wt % of a phenolic anti-oxidant.
 42. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid contains an anti-wear additive.
 43. The hydraulic fluid of claim 42 wherein the anti-wear additive contains an amine phosphate anti-wear additive and the hydraulic fluid further comprises up to about 1 wt % of the anti-wear additive(s).
 44. The hydraulic fluid of any preceding claim, wherein the hydraulic fluid contains a viscosity index improver.
 45. The hydraulic fluid of claim 44 wherein the hydraulic fluid contains at least 1 wt % of the viscosity index improver.
 46. In an apparatus comprising a pump lubricated by a hydraulic fluid, the improvement comprising a hydraulic fluid according to any of the preceding claims.
 47. In a gear system, circulation lubrication system, hydraulic system, compressor system, vacuum pump, metal working machinery, electrical switch or connector comprising a hydraulic fluid, the improvement comprising a hydraulic fluid according to any preceding claim. 